[mindwaves]

I know a fair amount of C and C++. Can I compile a program via the Terminal without using ProjectBuilder?

[Dalgo]

Yes, although I don't know why you'd want to. You can type your code in pretty much any ASCII text editor. If you want to do it all fram the terminal use emacs. Then to compile, simply go to the directory that you have your code and type cc mycodename. You should make sure that your files end in .h or.cpp or .m or whatever is appropriate or else it might not compile correctly. For C++, use the command c++ from the command line instead of cc. You can also do stuff with make files and the like but I don't know how those work.

[parallax]

You can. ProjectBuilder itself is simply an interface on top of cc and gdb.

You can use the cc command to compile C, and c++ to compile C++. If you are working on a large project from the command-line, it would be best to use a Makefile, which is explained at the immortal site:
http://www.cs.cf.ac.uk/Dave/C/CE.html