Along these same lines, the book Life Beyond Earth: The Intelligent Earthling's Guide to Life in the Universe by Gerald Feinberg and Robert Shapiro suggests some ways life, broadly defined, could exist.
Many people here probably don't have the time to read a book on an interesting, but non-practical topic. Can you give us a quick summary what are those ways?
I'm afraid I don't have time to summarize a 460+ page book full of complex ideas for those who won't make time to read it.