They've got great unique content. This is good for two reasons:

a) Google loves unique content. Unique content on old-world lyrics websites consists of comments buried under the fold. Whereas these guys have pages and subpages full of it.

b) They're going to get a bajillion inbound links because their content is interesting to link to (as opposed to standard lyrics sites). Which will rank them higher than their competitors for the same queries.

I see a lot of comparisons with Yelp. I still type in business names with "Yelp" appended into google because I want a specific result. Wouldn't be surprised if they're getting the same sort of queries already since what they have is so much better than any lyrics site.

Side note: I just opened AZ lyrics and some flash abomination nearly crashed my browser.