Plug-in for Visual Studio for quick-searching files in solution

Why re-invent the wheel? DevExpress + Microsoft tied up to offer CodeRush Express for free @ PDC2008 that does just that if I understand you correctly.

AFAIR I think the magic key combo for Jump to File is Ctrl+Alt+F and it does substring matches too. I tried it and it worked for me. Pretty nifty. Here's the link to a recording in case I goofed up on the actual keystroke... some really nice tips in it.

Update: Wrote a blog post for those who're short of time.

Visual Studio is already perfectly capable of doing that; just drag the "Edit.GoToFindCombo" to the toolbar, if it's not already there. (Press Ctrl+D if it is, to activate) and type ">of s" for all files starting with the letter 's'.

_{(source: aaronlerch.com)}

The GoToFindCombo is more powerful than this though, you can set aliases ">alias $aliasHere $SomeCommand" for virtually every command in Visual Studio. For example, to make an alias for find in files you type ">alias ff Edit.FindinFiles"

Sonic File Finder it's free

When you hit the shortcut you have a search box with autocomplete: alt text http://jens-schaller.de/files/images/SonicFileFinder/sonicFileFinderToolWindow.png

DPack really beats all of them (and moreover it's FREE).
Check out the Alt+U and Alt+M shortcuts (also I recommend others too).

Additionally I have found StudioTools to have very impressive GoTo feature if you want to jump to specific point (type member) in another file (really very fast).

NOTE: R# also has such feature but IMO it's weaker than DPack's version.