Bloodshot compilations are a cheap and easy way to sample a wide range of fabulous sounds. Some of the bands and artists you've heard of, some you haven't, but it is always worth checking them all out.
They are crammed full of a variety of artists and are VERY reasonably priced. The vast majority of the songs cannot be found anywhere else--people were kind enough to produce them solely for these releases.
There are thematic releases, as well as 5, 10, 15, 20 year anniversary discs. There's lots of intriguing covers, rare original material, serendipitous collaborations and lots of booklets and artwork.
We have to question your sanity if you don't take advantage of such an opportunity.
Well, duh, all of them...