Getting stack traces on Unix systems, automatically

Question

What methods are there for automatically getting a stack trace on Unix systems? I don't mean just getting a core file or attaching interactively with GDB, but having a SIGSEGV handler that dumps a backtrace to a text file.

Bonus points for the following optional features:

• Extra information gathering at crash time (eg. config files).
• Email a crash info bundle to the developers.
• Ability to add this in a dlopened shared library
• Not requiring a GUI