I've never played Touhou because I don't really like bullet hells, but the music from Touhou is just so dang good. I usually listen to the OST or (instrumental) fan arrangements while I work. My current favorites are Kuroneko Lounge's house set arrangements:
I'll throw my recommendation behind them as well, they are a really cool (and large) set of albums
Shame that the original artist doesn't sell many of them anymore