Sounds great on the NXT
What’s more, they are open source, and hosted with the Bricxcc suite of tools.
Among them are tools to convert a midi file to an NXT melody file with the .rmd extension, which can be renamed to rso files to be played back on the NXT. This, alongside a tool to convert wav files to rso files, and a tool to play back the rmd files makes for a good sound suite.
These utilities add to an already neat set of OSS tools, like BrickTool - which can deal with both the RCX and NXT, NeXTTool which is a suite designed for communicating with the NXT via Fantom and of course the Bricxcc Lego developer IDE itself.