If you want game play strategies, go here . Programming Resources TomScherrer Contains a most excellent assortment of Z80 information, including the TASM assembler and a Z80 Disassember . It also contains a lot of useful information for programming for the Z80. The king himself. Useful for quick hacks of romsets.
VI is a very powerful keyboard-based editor.
Mowerman's Mowerman's hardware info page. A great collection of information. I've since just given input about techniques to accomplish the goal, and have volunteered to work on the software. I still need to learn Z80 asm. It edits over 240 games, and will soon have Pacman map and text editing support thanks to yours truly.