Dan's Dreamcast Debugger - This is a simple assembly-level debugging front end to the GDB stub code. This uses the GDB protocol, so in theory it can be used with other GDB stubs for the SH4. The big difference is that it can't handle RLE compression, so if your stub uses that this won't work.
Debug Test Program - Another debug program by Dan.
Disassembly Tool - a modified version of bintools which allows it to correctly work with binary and elf files.
Dcdis 0.3.3a - Another disassembly tool this one created by Lars Olsson.
DCdisasm V 0.2a - This is an early test version of my SH4 (sh7091) CPU dissembler.
DreamICE - Another Dreamcast dissembler which is a lot like the legendary program called SoftICE for PC.