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Seconded! Highlighting brace pairs would also be a great feature.

On top of that, being able to collapse a brace-bounded region (or #region...#endregion tags in C#) would be nice, since we're on the subject :) May need to be a separate feature request.
Language-specific code format clean-up would be a fantastic feature. Curly-brace languages could line up brace pairs, HTML tags could get lined up, and code between the braces/tags could get indented to the same level.
Subversion would be amazing! I could enter the URL for my repository, browse the repository for a specific file, save it locally, make changes, then commit. The continuous integration process on the server would automatically build my changes for me so that they're ready to run when I return to my PC!
Code completion for C# (see MonoDevelop), PHP, HTML, JS, and CSS would be excellent.
I meant "right-most" key to display the next key set page. Tab should always be left-most.

Having customizable key sets would be the ultimate, but the interface for doing so may be too time-consuming for now. Selecting a different key set from the configuration view would be a good first-pass.