I have collections like Crime-Novel-Classic-Cultural-Info-German/French-Travel-Fantasy-Sci.Fi-Literature- New Books- Reading.
When a collection gets to big, I split it up in 4 or more parts: A-F, G-J etc. Except for Reading: about 13 books I'm currently reading.
I've some 30 collections and about 2000 books. ( Yes, I'll read anything not too offensive; moved to Fantasy and Sci.Fi. as well these last few years).