Second Life Regions or SIMs (need a list)?

Can anyone give me a list of the types of SIMs you can find on Second Life? I've been to a roaring 20's, cops & robbers, under the sea, vampyre, and a medieval SIM so far but I want to explore more. I know there is a Second Life search engine but you need a word or a phrase to start a search and I have nothing. I'm drawing a blank. I simply don't know where to start so can you brainstorm and give me some ideas?