Here is some of the software and hardware I have found useful in my tuning.
C.A.T.S. Tuner - http://www.tunercat.com
This editor covers a wide range of GM vehicles from the late 1980s to mid 1990s. It's free to try for 30 days and only $69 to buy, and each vehicle definition is $20.00. This program will only edit the binary image that is on your vehicles EPROM. However, 1994,1995 Camaro, Corvette, Trans-Am, Impala LT1 vehicles can be edited directly through the ALDL connector under the steering column. All other applications will require the use of a EPROM chip burner.
TunerPro - http://www.tunerpro.markmansur.com
This editor is very similar to C.A.T.S. Tuner, but free with no expiration. Definitions are also free, but, as most of them where created by people other then the Tuner Pro author, the accuracy is not guaranteed. This will not flash 94-95 LT1.
Dual Power Willem Universal EPROM Programmer - http://www.mcumall.com
With this programmer you can read, EPROMs used by the GM ECM's. It's software will tell you the correct settings for a very wide range of EPROM'S that are compatible with the programmer. Cost is only $42.99 This programmer is cheap and works very well for what I am doing. This will also program the replacement chip used to put your custom tune on.
ALDL Interface Cable - http://www.akmcables.com/assembly.htm
Interface cable that goes from computer serial port (COM1) to your OBD-I diagnostic port. You can buy a ready to go one, or order a kit, or get the schematic and build it completely your self! $35 for unassembled kit, or $95 for complete ready to go. You can also get the OBD-I and OBD-II connectors by them selves. 1995 Camaro/Firebird used a OBD2 style plug, but were OBD1 vehicles. Don't be confused thinking this interface will work with 96+ OBD2, IT WILL NOT.
Moates.Net - http://www.moates.net
This website has a lot of hardware needed for tuning a lot of different stuff, not only GM. For my programming needs, this is the hardware I purchased from Moates.net