16.1 Debugging
OllyDbgis what most people have as an entry level tool and it provides a nice disassembler and basic debugging/listing tools.
Cheat engine works in a similar manner to the likes of emuhaste covered back in cheat making.
Further down the line you have things like
DLL export viewer to get a rough idea of what the DLL files input options (and function names) and scope is.
GDIView (open fonts and what they are set as and similar things)
Device IO viewer for when you need to reverse engineer drivers.
Nirsoft opened files viewer to know what programs have opened what and there is also Process explorer which does similar things.
Rec attempts to turn programs developed in C back into something resembling source code.
As mentioned the big tool that most people eventually wind up with a copy of though is IDA as it is both disassembler and debugger which allows for a lot of abilities here.