diff --git a/doc.go b/doc.go
index 2b22967..284aa84 100644
--- a/doc.go
+++ b/doc.go
@@ -36,14 +36,14 @@ package goquery
 // x Find() : Complete with Selection object and Node object as selectors - Tree Traversal
 // x First() - Filtering
 // x Get() - Node (DOM) Manipulation
-// - Has() - Filtering
+// x Has() - Filtering
 // x HasClass() - Attributes
 // - Html() ? - Attributes
 // - Index() - DOM Manipulation
 // - Is() - Filtering
-// - Last() - Filtering
-// - Length() / Size() - jQUery property
-// - Map() - Filtering
+// x Last() - Filtering
+// x Length() / Size() - jQUery property
+// x Map() - Filtering
 // - Next() - Tree traversal
 // - NextAll() - Tree traversal
 // - NextUntil() - Tree traversal
diff --git a/each.go b/each.go
index 1a40ca8..47b037d 100644
--- a/each.go
+++ b/each.go
@@ -7,3 +7,13 @@ func (this *Selection) Each(f func(int, *Selection)) *Selection {
 	}
 	return this
 }
+
+// Map() passes each element in the current matched set through a function,
+// producing a slice of string holding the returned values.
+func (this *Selection) Map(f func(int, *Selection) string) (result []string) {
+	for i, n := range this.Nodes {
+		result = append(result, f(i, newSingleSelection(n, this.document)))
+	}
+
+	return result
+}
diff --git a/filter.go b/filter.go
index 9fea878..7fe5108 100644
--- a/filter.go
+++ b/filter.go
@@ -60,8 +60,22 @@ func (this *Selection) FilterSelection(s *Selection) *Selection {
 func (this *Selection) Has(selector string) *Selection {
 	sel := this.document.Find(selector)
 
+	return this.HasSelection(sel)
+}
+
+func (this *Selection) HasNode(node *html.Node) *Selection {
 	return this.FilterFunction(func(_ int, s *Selection) bool {
-		// Add all nodes that contain one of the nodes selected by the Has() selector
+		// Add all nodes that contain the node specified
+		if s.Contains(node) {
+			return true
+		}
+		return false
+	})
+}
+
+func (this *Selection) HasSelection(sel *Selection) *Selection {
+	return this.FilterFunction(func(_ int, s *Selection) bool {
+		// Add all nodes that contain one of the nodes in the selection
 		for _, n := range sel.Nodes {
 			if s.Contains(n) {
 				return true
diff --git a/first.go b/first.go
index 5f7569c..4babb05 100644
--- a/first.go
+++ b/first.go
@@ -3,10 +3,13 @@ package goquery
 // First() reduces the set of matched elements to the first in the set.
 // It returns a new Selection object.
 func (this *Selection) First() *Selection {
-	if len(this.Nodes) == 0 {
-		return newEmptySelection(this.document)
-	}
-	return newSingleSelection(this.Nodes[0], this.document)
+	return this.Eq(0)
+}
+
+// Last() reduces the set of matched elements to the last in the set.
+// It returns a new Selection object.
+func (this *Selection) Last() *Selection {
+	return this.Eq(-1)
 }
 
 // Eq() reduces the set of matched elements to the one at the specified index.
diff --git a/iterators.go b/iterators.go
new file mode 100644
index 0000000..1a40ca8
--- /dev/null
+++ b/iterators.go
@@ -0,0 +1,9 @@
+package goquery
+
+// Returns this (same Selection object)
+func (this *Selection) Each(f func(int, *Selection)) *Selection {
+	for i, n := range this.Nodes {
+		f(i, newSingleSelection(n, this.document))
+	}
+	return this
+}
diff --git a/selection.go b/selection.go
index b1d4d90..bb17658 100644
--- a/selection.go
+++ b/selection.go
@@ -7,6 +7,15 @@ import (
 type Selection struct {
 	Nodes    []*html.Node
 	document *Document
+	prevSel  *Selection
+}
+
+func (this *Selection) Size() int {
+	return this.Length()
+}
+
+func (this *Selection) Length() int {
+	return len(this.Nodes)
 }
 
 func newEmptySelection(doc *Document) *Selection {