I think the competition in Silverlight Controls market will be fierce. Just under a few months, developers have created a handful of UI controls for Silverlight 2.0 already. Well, some like VectorLight provides it for free with full source code (maybe for now?). The VectorLight's controls set include Calendar, Dropdown List, Fieldset, ListBox, Textbox, TextArea, Tree View, Progress Bar, and Text Label.

VectorLight Controls Demo 

Free Silverlight controls are popping up a lot lately, especially WinForms-like and charting controls. Here's another chart conrol The FreeSilverlightChart by Venkata Guddanti. It uses XAML and C# to display charts on the Silverlight platform. The FreeSilverlightChart Control supports quite a lot of chart types including: Verticle Bar, Cylinder Bar, Horizontal Bar, Stacked Vertical Bar, Stacked Horizontal Bar, Pie, Area, Stacked Area, Line, Bar & Line, Area & Line, Bar/Area/Line, XY Line, Scatter Plot, Radar, Radar/Area, Funnel, Circular Gauge, Semi-Circular Gauge. 

Online Demo - Source Code

This clock is definitely not for instant use on your website. This sample is intended for showing how to rotate the clock's arm and simulate Timer control from timeline control.

Online Demo -  C# Source Code - VB.NET Source Code

It's no surprise that enterprise developers are putting a lot of investments in Silverlight. ComponentOne is no different from the others. It's just they have created the first clone of Google Finance Chart in Silverlight. Meet ComponentOne's Stock Portfolio Manager Demo which features stock chart with interactive scroll and zoom.

Telerik an awards-winning producer of ASP.NET Controls has made the demos of their Silverlight controls available online. The actual controls are not released yet, but in the demos you can view the related XAML and C# markup. The demos feature the following controls: RadAnimations, RadButtons (6 types), RadCombobox, RadListBox, RadMenu, RadProgressBar, RadSlider, RadTabStrip, RadTextBox, RadTreeView and RadUpload.

More details from Todd Anglin's blog post.