diff --git a/src/components/main/layout/floats.rs b/src/components/main/layout/floats.rs
index 4f58da33e33..db8bc67101f 100644
--- a/src/components/main/layout/floats.rs
+++ b/src/components/main/layout/floats.rs
@@ -8,6 +8,7 @@ use geom::size::Size2D;
 use servo_util::cowarc::CowArc;
 use servo_util::geometry::{Au, max, min};
 use std::i32;
+use std::fmt;
 use style::computed_values::float;
 
 /// The kind of float: left or right.
@@ -43,6 +44,12 @@ struct Float {
     kind: FloatKind,
 }
 
+impl fmt::Show for Float {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f.buf, "bounds={} kind={:?}", self.bounds, self.kind)
+    }
+}
+
 /// Information about the floats next to a flow.
 ///
 /// FIXME(pcwalton): When we have fast `MutexArc`s, try removing `#[deriving(Clone)]` and wrap in a
@@ -64,6 +71,12 @@ impl FloatList {
     }
 }
 
+impl fmt::Show for FloatList {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f.buf, "max_top={} floats={:?}", self.max_top, self.floats)
+    }
+}
+
 /// Wraps a `FloatList` to avoid allocation in the common case of no floats.
 ///
 /// FIXME(pcwalton): When we have fast `MutexArc`s, try removing `CowArc` and use a mutex instead.
@@ -114,6 +127,12 @@ pub struct PlacementInfo {
     pub kind: FloatKind
 }
 
+impl fmt::Show for PlacementInfo {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f.buf, "size={} ceiling={} max_width={} kind={:?}", self.size, self.ceiling, self.max_width, self.kind)
+    }
+}
+
 fn range_intersect(top_1: Au, bottom_1: Au, top_2: Au, bottom_2: Au) -> (Au, Au) {
     (max(top_1, top_2), min(bottom_1, bottom_2))
 }
@@ -128,6 +147,19 @@ pub struct Floats {
     offset: Point2D<Au>,
 }
 
+impl fmt::Show for Floats {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self.list.get() {
+            None => {
+                write!(f.buf, "[empty]")
+            }
+            Some(list) => {
+                write!(f.buf, "offset={} floats={}", self.offset, list)
+            }
+        }
+    }
+}
+
 impl Floats {
     /// Creates a new `Floats` object.
     pub fn new() -> Floats {
diff --git a/src/components/main/layout/model.rs b/src/components/main/layout/model.rs
index 3fda7357fe7..b1a759286dc 100644
--- a/src/components/main/layout/model.rs
+++ b/src/components/main/layout/model.rs
@@ -12,6 +12,7 @@ use style::computed_values::{LPA_Auto, LPA_Length, LPA_Percentage, LP_Length, LP
 use style::ComputedValues;
 use servo_util::geometry::Au;
 use servo_util::geometry;
+use std::fmt;
 
 /// A collapsible margin. See CSS 2.1 § 8.3.1.
 pub struct AdjoiningMargins {
@@ -249,6 +250,12 @@ pub struct IntrinsicWidths {
     pub surround_width: Au,
 }
 
+impl fmt::Show for IntrinsicWidths {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f.buf, "min={}, pref={}, surr={}", self.minimum_width, self.preferred_width, self.surround_width)
+    }
+}
+
 impl IntrinsicWidths {
     pub fn new() -> IntrinsicWidths {
         IntrinsicWidths {
diff --git a/src/components/util/geometry.rs b/src/components/util/geometry.rs
index f1dd2d816ce..f63b7aa1cce 100644
--- a/src/components/util/geometry.rs
+++ b/src/components/util/geometry.rs
@@ -25,7 +25,7 @@ impl Default for Au {
 impl fmt::Show for Au {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let Au(n) = *self;
-        write!(f.buf, "Au({})", n)
+        write!(f.buf, "Au(au={} px={})", n, to_frac_px(*self))
     }}
 
 impl Add<Au,Au> for Au {