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 

Pete Brown is showing how to handle multiple screens (like Wizard control) and modal dialog in Silverlight. The pattern illustrated provides a way to simulate windows in what is inherently a non-windowed system: the Silverlight plug-in running inside the browser.

Online Demo - Source Code - Direct Download

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

Visual WebGui is an open source AJAX framework, targeted at enabling smooth fast and risk free framework to enable AJAX / Silverlight for complex, data intensive IT level application GUI. Visual WebGui AJAX framework is based on a revolutionary ON-Server approach that offers the highest simplicity in designing and programming, secured front ends and industrial strength that allows unlimited application size and weight on web.

Visual WebGui Features

• AJAX application development using WinForms development patterns and practices with no prior AJAX (or web development) skills.
• WinForms controls (most of .NET 2.0 controls) implemented for VWG.
• Ability to create custom controls (including full inheritance).
• Ability to interoperate with existing ASP.NET controls and pages.
• Ability to customize control behavior and appearance.
• .NET 1.x/2.0 support.

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.

NETiKA Technologies has developed a set of controls that has WinForms Controls' look-and-feel for Microsoft Silverlight (and Adobe Flash). From their live demos, you can see buttons, checkboxes, textboxes, menus, lists, treeviews, tabs, toolbars, calendars and even DataGrids! It is pretty impressive that they did it before Microsoft does. Formal WinForms-like controls are expected to be shipped by Microsoft for Silverlight 2.0.