Recently I've been scavenging around and I've found some interesting tools I'd like to share. :]
Coccinelle - a 'semantic patch' based framework - you can think of it like a super-uber-enhanced version of GNU patch. The primary motivation AFAICS, as seen on the page, is semantic patching of e.g. Linux drivers. You'll really just have to go to the webpage and see an example/read a little to get an idea of how it works because I can't explain it too well, but it's an amazingly innovative and cool idea.
Frama-C - a framework for C source code analysis; has a lot of really interesting tools, the two catching my eye the most being:
* Jessie/ACSL - A plugin for formally proving properties about your programs.
* Slicing - a plugin allowing you to...
On the note of ACSL, you may also find Deputy interesting; it's a C compiler (gcc-compatible) that allows you to annotate your programs for safety measures. Apparently Linux drivers etc. were also a motivation for this project. I might as well also throw the Clang static analyzer out there; it has the advantage it can check C and objective-C programs (and once support gets better, C++ as well hopefully.) If you also don't know about clang/llvm, then you should educate yourself because they are both awesome (I hope clang is the death of GCC, personally.)... produce an output program which is made of a subset of the statements of the analyzed program, in the same order as in the analyzed program. The statements are selected according to a user-provided slicing criterion. The output program is guaranteed to be compilable C code, and to have the same behavior as the analyzed program from the point of view of the provided slicing criterion.
Also, for large code bases (I'm talking in the 10-20 million line range, like linux or something,) you would be a fool not to have cscope (I've known about/used cscope for years; I mention it because it does not get enough love!)
Currently I'm writing a garbage collector in C, and I think ACSL and/or deputy could help out a lot hopefully...
Does anybody else have any interesting tools they've recently found and would like to share?