I use the well know resources: wikipedia, a few web sites with many hash functions benchmarked that will show up if you google "hash functions".

However this is very interesting IMHO if you want to understand the inner working of CRC: http://www.ross.net/crc/crcpaper.html

If you are interested in cryptographic hash functions a good introduction is "Applied Cryptography" that can be integrated with "Handbook of Applied Cryptography" (all chapters free here: http://www.cacr.math.uwaterloo.ca/hac/).