Top 20 NuGet XAML Packages

A simple and customizable converter/extension from bool to Visibility for Wpf/XAML. It offers a markup extension (so you can use it inline in XAML without defining a resource) and easy custumizability of the conversion.

XAML Operations Binding Library

XAML based calendar control for WinRT / Windows Store Style application. Supports full custom styling and comes with a template you can easily customize. Supports all modes, including snapped with the default template.

RichTextBlock.Html2Xaml adds a Html property to RichTextBlock controls, that translates Html formatted text on the fly to the subset of XAML that the RichTextBlock control supports, with just two source files that are simple to modify: one C#, one XSLT.

Part of the Coding4Fun Toolkit for Windows Phone with only the Network library. Items such as a GzipWebClient are in it.

Part of the Coding4Fun Toolkit with only the Storage library. It provides an easy to use wrapper open and save data via serialization.

Collection of WPF shape controls

A collection of universally useful XAML value converters, behaviors, and styles.

A custom View Engine for ASP.NET MVC (2.0, 3.0 or newer) that allows Controller Action Methods to return dynamically generated images based on XAML markup. This requires .NET 4.0 or later.

Xaml based configuaration for the Enterprise Library Unity Application Block. Works both for the server and the client.

A control suite for some common things a Windows 8.1 XAML application might want to include such as a Flyout, Menu, Rating, Settings Pane, and other controls.

A Custom Content Control for Windows 8 app Settings Charm Flyouts.

A Metro Panning Custom Control

A Metro moving background

Multiple Platforms: GetElementRect, GetVisualChild, GetVisualAncestor, Enum extensions, RelayCommand, PropertyChangedBase Windows 8: Flyout, SettingsContractWrapper, LabeledProgressBar, KeyboardKiller Windows Phone: ReverseAutocompletePopup, StatusBarExtensions, CustomMessageBox .NET4.5: CustomMe...

Bob wasn't a great product for Microsoft but maybe Bob can add what's missing for Windows 8

Gauge control for Windows Phone 8.1.

A set of controls, extensions and helper classes for Windows Runtime XAML applications.