Emacs

ALT-x gdb
Run GDB under Emacs.
CTL-h m  
Describe GDB mode.
ALT-s step
Step one line.
ALT-n next
Next line.
ALT-i stepi
Step one instruction.
CTL-c CTL-f finish
Finish current stack frame.
ALT-c up
Up arg frames.
ALT-d down
Down arg frames.
CTL-x &  
Copy number from point, insert at end.
CTL-x SPC  
Set break at point (in source file).