What are the most useful keyboard shortcuts for visual c++ 2008?

Have a look at this (there's a nicer version for VS 2010, it's probably virtually the same set of keybindings).

commented: THanks Jonsca +1

Of all those, I only use F5, F5, F9, F10 and F11 because those are the ones for compiling and debugging. I also like Ctrl+[ and Ctrl+] keys, which are macros for finding beginning and ending {, [ and (

This isn't a Visual Studio thing, but the home key group is your BEST friend.

Home & end will move to the beginning and end of a line, page up & page down scroll pages at a time.

Shift + (home || end) will highlight an entire line,
Ctrl + (left arrow || right arrow) will move the cursor a word at a time.
Ctrl + Shift + (left arrow || right arrow) will highlight a word at a time.

and the "delete" key I also find very useful, it's like the backspace key except it deletes the character in FRONT of the cursor. When navigating text with my arrow keys the delete key is very close by also.

Unfortunately I haven't found a good use for "insert" mode yet... I don't know that I ever will, I think it is really just useless.