Xceed DataGrid for Silverlight

On-demand data retrieval (data virtualization) ensures that only records that are visible are requested from the server.

This greatly reduces the amount of data to be transferred, which increases the perceived speed of the datagrid. Also reduces strain on the server.
The only Silverlight datagrid to display remote data blazingly fast, thanks to its powerful background (asynchronous) record retrieval system! (See it in action.)
Data virtualization is presented through a convenient infinite scrolling scrollbar experience instead of the typical Web-grid paging interface.
An ingenious design uses passive pre-fetching in the background to cache records before and after the ones currently being requested, so when scrolling or paging up or down, the end-user instantly sees the data: there are no just-in-time requests that make the end-user wait, which makes your application feel sluggish.
Active pre-fetching is used to keep the cache full when the datagrid is idle.
Asynchronous (background) data requests keep the UI responsive at all times. No other datagrid currently on the market does this.
Enabled for all of the datagrid’s features, so there’s no trade-off between capabilities and performance.
The datagrid supports WCF Data Services and WCF RIA Services, so developers get all the advantages of this system with just a few lines of code.
Supports practically any type of custom data source. For example, provide code to access Twitter for the appropriate event, and the datagrid can consume and display that kind of data with all the benefits of data virtualization.
Supports SQL databases and remote lists. (New in v1.3)
Can even provide data virtualization for streams and other “endless” sources, such as forums and blogs!