Doujin is awesome. For more great arrangements, check out Magical Trick Society, Low-Tech Son, Demetori, Germania Monte Mario, Best of Shape, Dorothy's Cafe, CROW'SCLAW, takrockers!!, and ViViX/Godspeed/Serenade (I'd also suggest Fumapero and Sepia'n Gamers+, but they sadly went away awhile ago. You might still be able to find tracks from the floating around these here 'tubes, though). The pages are in Japanese, but just find links to MP3s and you're golden. Lots of excellent stuff to be found from Japanese VGM arrangers.