I'm looking at C again after about 15 years, so I figured trying the Project Euler problems would be a good start for getting back into the language. I don't have any particular reason for getting back into C, so I don't know how frequently I'll actually look at these, but the first milestone is to have the first 100 done.
You can run any of these, if you really want to, using gcc like so, on a Posix or posix-esque system.
$ gcc FILENAME -o OUTPUTBINARYFILENAME
None of them are dependant on non-standard libraries, or even much more than stdio, stdlib, and maybe string, so you shouldn't have any problems.
If you encounter any issue, please don't hesitate to contact someone else for help ;)