RomRaider

Since the licenses for IDA Pro are so expensive and it's "difficult" to obtain, I found an online disassembler that might be useful to get more of us into hacking with the ROMs:

https://www.onlinedisassembler.com/

Did a quick check and they support sh4 processors. Haven't dug much into it yet, but hopefully someone with more experience with disassembly can play with it and let us know if it's worth using.

Also found this which apparently supports SH architecture (not sure if it supports SH4 specifically) - it has a web GUI, I will throw it on my web server later and post up the link:
http://www.radare.org/r/index.html