Whether searching for authors/books or obscure themes within the genre, the SFE offers a huge (and free) database. If you're new to Science Fiction--reading or writing--and don't understand a particular concept, this online reference is a great place to start. Several of the themes and/or keywords can even inspire stories in their own right. Wanna know what a Jonbar Point is? A Kipple?
Check it out writers: http://http//sf-encyclopedia.com/category/themes/theme