SampleLab's iLoops features samples from four of their previous releases and is most likely to appeal to GarageBand users.
Broken Beats covers acoustic bass and lo-fi drum loops; Luscious Grooves is a slightly more varied collection of beats; Discography is straight up disco; and Spatial Awareness is more ambient.
Sadly, the loops are no better than average, particularly the drums. These don't really adhere to any particular genres and for the most part are uninspiring.
The acoustic bass loops are OK and some of the ambient sounds are quite good – but on the whole this is a dull collection indeed.