Hunting for buffer overflows

Is there a way to use a debugger (immunity preferably but I'll take gdb or any other debugger you know how to do this with) so that any time a piece of memory holds a particular value (say AAAAAAAA) the debugger will make a note of what line it happened and then continue on until it fully crashes.

Not just a simple watch but anytime any register or memory in use by the program contains an A to make a notation of this.  It seems like a really good idea that would take some of the hard work out of exploit development but I have yet to see any straightforward talk of this.

>>5
Ahh ok I think that the bochs debugger is supposed to be scriptable.  Since you were able to answer this with so much certainty and because this feature doesn't seem to already exist I have to assume this is because of the way debuggers work.

Well I guess now it's just a toss up between writing some sort of script that goes through the entire memory space and sets watches or scripting the bochs debugger (which I suspect will have a steeper learning curve), slowness isn't a factor since this will allow automated fuzzing with a great deal of the work already done for me I can just queue a bunch of software up on a box somewhere and check the results whenever I'm motivated and have the time to try and crack something.