I've seen requests for a portable C++ comiler and saw the thread about Bloodshed Dev and how the problem with it is that it is so HUGE...
Well this isn't a C++ compiler but it does do C. It is also tiny as one might guess by it's name (it will fit on a floppy disk!). It was made for Posix platforms but has recently been ported to Windows using the MinGW includes.
I have been using it to learn the C language and it works great for me. I even setup an IDE for it by coupling it with the Jen's File Editor and even have added some other GNU Win32 Tools and tools for MinGW that are called through JFE.
Since I am a beginner, I probably haven't set up JFE and additional tools to work to work optimally for a more learned programmer, but for some one on that level to do it would probably take but a few hours.
Anyway, just a suggestion.