I just bought Module Player for Iphone, it is awesome! Access to Modland database is built-in with on-demand download of mods!
My only gripe is that mods are sorted by author name, not game name. However, you can search for a game name. Then if you find the mod you were looking for, you can double click it to list all the mods by same author, which is a great way to discover new mods.
I love listening to "thesettlers", the 12 min in game music is amazing and seemingly never ends. Or Leander World 1
Also great: "Sid Player" by the same author, with on-demand download of c64 tunes from the HVSC collection!