Cryptography is a way of hiding information which is much needed in today's society. It's used daily in passwords, debit cards and any type of electronic commerce. If you're looking to get into a field of demand, this would be a good one! There is a website that has a library of algorithm source codes available. A good number of them are free, but there are some where only the binary versions are
. free. You can find the site here: http://www.thefreecountry.com/sourcecode/encryption.shtml.