I have used quite a few of the techniques listed here including...
The thesaurus method:
Just the other day, I was trying to find a domain for my new recipe site, and I wanted something like lazychef.com but all the relevant names were taken. Not only that, but I didn't want to modify it by adding NewLazyChef or anything like either that since Lazy Chef was already kind of branded. And the same was true for a bunch of alternative phrases.
So I went to the thesaurus... and came up with a not terribly keyword friendly but definitely memorable name:
LackadaisicalChef.com (site will be set up "next year"!
I bet no one is looking for that keyword, but once I've published a few Kindle books with that name and a few Videos, oh, and spread it around on Pinterest, I think word will get out.
About non-.com domains...
Also, while I rarely use .net and .org (though I used to), I do occasionally use .info, especially when it makes sense (with info focused sites) and I can't get the .com
I found that they can rank just as well as .com sites as long as they're keyword optimized and have quality content.