In case anyone wants to know, I put some looping vorbis OGGs up in the appropriate resources section. I have some others, but I figured I should wait a little before sharing.
Do note that if you try to play them with a plain OGG player (I.E. WinAmp), they won't loop properly; they need to be played with a vorbis OGG player. Which, fortunately, RMXP and RMVX have built-in vorbis players, so they'll loop correctly. Just play 'em in the Sound Test of those two engines if you don't believe me.
Thanks to From Ariel for adding the OGG section after I asked for it.