NES Utilities

Program Download Description
CajoNES

Download I've heard many a good thing about this ROM utility, but I've never actually used it. This is the final release.
Famicon Converter Download Changes pasofami formatted NES ROMs to Famicon format.
Fix Download Fixes mapper problems for NES ROMs for iNES .7 and NESticle .4
Graphics Extractor Download This is a program written by Jair that rips the graphics from a ROM and dumps them into a BMP file. Use the Graphics Inserter to stick them back in.
Graphics Inserter Download This goes along with the Graphics Extractor. You can poke in BMP images with it as well as reinserting graphics you extracted.
Hexposure Download Many ROM hackers will tell you this is their favorite hex editor. It has good table support and a relative searcher built in. A must-have tool for any ROM hacker.
NESimage Download Converts ROMs back and forth from iNES, Pasofami, and FFE.
NESToy Download

Download (Windows)
A utility that can do many things to NES ROMs, including renaming, repairing, and identifying.
There's also a Windows port that has the same capabilities as its DOS counterpart.
Nosefart Download

Download (WinAMP plug-in)
This is, in my opinion, the best NSF player out there. It's for DOS and has visualization and the ability to turn off sound channels.
There's also this WinAMP plug-in that works about as well as the DOS version.
NSF Tool Download A small utility that lets you rename NSF files and view information about it.
QND Download Another ROM manipulation utility. It's been discontinued though.
ReadChar Download A utility that allows you to look at the NES ROM's sprite data. It doesn't let you edit the sprites at all though.
TetaNES Download A useful tool that converts ROMs to different formats.
Tile Layer Download This is THE sprite editor of choice for most ROM hackers. It has support for 1BPP, NES, SNES, SMS, Virtual Boy ,and Gameboy tiles.

tniNES Download Similar to NESimage, it edits the header format of the ROM. It also has various other features.
TRaCER Download A disassembler that was programmed by Y0SHi. I can't really judge how good it is though, since I don't know any ASM...
X816 Assembler Download Again, thanks to my lack of ASM knowledge, I really can't say how good this thing is. Try it for yourself.
Xchar Download I could never get it to work on my PC, but from what I hear it's a decent tile editor.
6502 Disassembler Download Another utility that uses ASM, which I don't know. It might be good, but you ASM people will have to figure it out for yourselves.