diff --git a/src/Collections/Comparable.php b/src/Collections/Comparable.php
new file mode 100644
--- /dev/null
+++ b/src/Collections/Comparable.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Keruald\OmniTools\Collections;
+
+interface Comparable {
+
+    public function compareTo (object $other) : int;
+
+}
diff --git a/src/Collections/WeightedList.php b/src/Collections/WeightedList.php
new file mode 100644
--- /dev/null
+++ b/src/Collections/WeightedList.php
@@ -0,0 +1,75 @@
+<?php
+
+namespace Keruald\OmniTools\Collections;
+
+use ArrayIterator;
+use Countable;
+use Iterator;
+use IteratorAggregate;
+
+class WeightedList implements IteratorAggregate, Countable {
+
+    /**
+     * @var WeightedValue[]
+     */
+    private $list;
+
+    public function __construct () {
+        $this->list = [];
+    }
+
+    ///
+    /// Helper methods
+    ///
+
+    public function add ($item, float $weight = 1.0) : void {
+        $this->list[] = new WeightedValue($item, $weight);
+    }
+
+    public function clear () : void {
+        $this->list = [];
+    }
+
+    public function getHeaviest () {
+        $value = null;
+
+        foreach ($this->list as $candidate) {
+            if ($value === null || $candidate->compareTo($value) > 0) {
+                $value = $candidate;
+            }
+        }
+
+        return $value;
+    }
+
+    public function toSortedArray () : array {
+        $weights = [];
+        $values = [];
+
+        foreach ($this->list as $item) {
+            $weights[] = $item->getWeight();
+            $values[] = $item->getValue();
+        }
+
+        array_multisort($weights, SORT_DESC, $values, SORT_ASC);
+
+        return $values;
+    }
+
+    ///
+    /// IteratorAggregate implementation
+    ///
+
+    public function getIterator () : Iterator {
+        return new ArrayIterator($this->list);
+    }
+
+    ///
+    /// Countable implementation
+    ///
+
+    public function count () : int {
+        return count($this->list);
+    }
+
+}
diff --git a/src/Collections/WeightedValue.php b/src/Collections/WeightedValue.php
new file mode 100644
--- /dev/null
+++ b/src/Collections/WeightedValue.php
@@ -0,0 +1,75 @@
+<?php
+declare(strict_types=1);
+
+namespace Keruald\OmniTools\Collections;
+
+use TypeError;
+
+class WeightedValue implements Comparable {
+
+    ///
+    /// Constants
+    ///
+
+    const DEFAULT_WEIGHT = 1.0;
+
+    ///
+    /// Private members
+    ///
+
+    /**
+     * @var float
+     */
+    private $weight = self::DEFAULT_WEIGHT;
+
+    /**
+     * @var mixed
+     */
+    private $value;
+
+    ///
+    /// Constructor
+    ///
+
+    public function __construct ($value, float $weight = self::DEFAULT_WEIGHT) {
+        $this->value = $value;
+        $this->weight = $weight;
+    }
+
+    ///
+    /// Getters and setters
+    ///
+
+    public function getWeight () : float {
+        return $this->weight;
+    }
+
+    public function setWeight (float $weight) : self {
+        $this->weight = $weight;
+
+        return $this;
+    }
+
+    public function getValue () {
+        return $this->value;
+    }
+
+    public function setValue ($value) : self {
+        $this->value = $value;
+
+        return $this;
+    }
+
+    ///
+    /// Helper methods
+    ///
+
+    public function compareTo (object $other) : int {
+        if (!$other instanceof WeightedValue) {
+            throw new TypeError;
+        }
+
+        return $this->getWeight() <=> $other->getWeight();
+    }
+
+}
diff --git a/tests/Collections/WeightedListTest.php b/tests/Collections/WeightedListTest.php
new file mode 100644
--- /dev/null
+++ b/tests/Collections/WeightedListTest.php
@@ -0,0 +1,79 @@
+<?php
+declare(strict_types=1);
+
+namespace Keruald\OmniTools\Tests\Collections;
+
+use Keruald\OmniTools\Collections\WeightedValue;
+use Keruald\OmniTools\Collections\WeightedList;
+use PHPUnit\Framework\TestCase;
+
+class WeightedListTest extends TestCase {
+
+    /**
+     * @var WeightedList
+     */
+    private $list;
+
+    ///
+    /// Fixtures
+    ///
+
+    protected function setUp () : void {
+        $this->list = new WeightedList;
+        $this->list->add("LOW", 0.1);
+        $this->list->add("HIGH", 4);
+        $this->list->add("AVERAGE");
+    }
+
+    ///
+    /// Tests
+    ///
+
+    public function testAdd () : void {
+        $count = count($this->list);
+
+        $this->list->add("ANOTHER");
+
+        $this->assertEquals($count + 1, count($this->list));
+    }
+
+    public function testClear () : void {
+        $this->list->clear();
+        $this->assertEquals(0, count($this->list));
+    }
+
+    public function testGetHeaviest () : void {
+        $this->assertEquals(4, $this->list->getHeaviest()->getWeight());
+    }
+
+    public function testToSortedArray () : void {
+        $array = $this->list->toSortedArray();
+
+        $this->assertEquals(3, count($array));
+        $this->assertEquals(["HIGH", "AVERAGE", "LOW"], $array);
+    }
+
+    public function testToSortedArrayWithDuplicateValues () : void {
+        $this->list->add("AVERAGE");
+        $array = $this->list->toSortedArray();
+
+        $this->assertEquals(4, count($array));
+        $this->assertEquals(["HIGH", "AVERAGE", "AVERAGE", "LOW"], $array);
+    }
+
+    public function testGetIterator () : void {
+        $count = 0;
+
+        foreach ($this->list as $item) {
+            $this->assertInstanceOf(WeightedValue::class, $item);
+            $count++;
+        }
+
+        $this->assertEquals(3, $count);
+    }
+
+    public function testCount() : void {
+        $this->assertEquals(3, $this->list->count());
+    }
+
+}
diff --git a/tests/Collections/WeightedValueTest.php b/tests/Collections/WeightedValueTest.php
new file mode 100644
--- /dev/null
+++ b/tests/Collections/WeightedValueTest.php
@@ -0,0 +1,79 @@
+<?php
+declare(strict_types=1);
+
+namespace Keruald\OmniTools\Tests\Collections;
+
+use Keruald\OmniTools\Collections\WeightedValue;
+use PHPUnit\Framework\TestCase;
+
+class WeightedValueTest extends TestCase {
+
+    /**
+     * @var WeightedValue
+     */
+    private $lowValue;
+
+    /**
+     * @var WeightedValue
+     */
+    private $highValue;
+
+    ///
+    /// Fixtures
+    ///
+
+    protected function setUp () : void {
+        $this->lowValue = new WeightedValue("LOW", 0.1);
+        $this->highValue = new WeightedValue("HIGH");
+    }
+
+    ///
+    /// Tests
+    ///
+
+    public function testGetWeight () : void {
+        $this->assertSame(0.1, $this->lowValue->getWeight());
+        $this->assertSame(
+            WeightedValue::DEFAULT_WEIGHT,
+            $this->highValue->getWeight()
+        );
+    }
+
+    public function testSetWeight () : void {
+        $this->lowValue->setWeight(0.2);
+        $this->assertSame(0.2, $this->lowValue->getWeight());
+    }
+
+    public function testGetValue () : void {
+        $this->assertEquals("LOW", $this->lowValue->getValue());
+        $this->assertEquals("HIGH", $this->highValue->getValue());
+    }
+
+    public function testSetValue () : void {
+        $this->lowValue->setValue("FOO");
+        $this->assertEquals("FOO", $this->lowValue->getValue());
+    }
+
+    public function testCompareTo () : void {
+        $this->assertEquals(
+            0,
+            $this->lowValue->compareTo($this->lowValue)
+        );
+
+        $this->assertEquals(
+            -1,
+            $this->lowValue->compareTo($this->highValue)
+        );
+
+        $this->assertEquals(
+            1,
+            $this->highValue->compareTo($this->lowValue)
+        );
+    }
+
+    public function testCompareToWithApplesAndPears () : void {
+        $this->expectException("TypeError");
+        $this->highValue->compareTo(new \stdClass);
+    }
+
+}