Loop libraries....

[CHuckmott]

Starting to see where some good loop libraries (like the nine volt audio) can be very inspirational, even the ones that feature my main instrument , to write tracks and songs around. So the question comes in 3 parts: Can we recommend some good looping sites? Are there any caveats or things to be aware of when using purchased loops in your tracks? I could see myself using pieces here and there, but does anybody have some examples where they may have used several parts or even some tracks composed entirely from loops? Thanks. My main loop player BTW would be Stylus RMX.