Code Challenge: Fun with Hash

No, this is not what you expected, crackhead. This post doesn't include getting high on anything stronger than your coding skills. It's time for another code challenge!

The challenge
Sometimes it can be very handy to make a small fingerprint of a piece of textual information so you can easily compare it to other pieces of text and check if they are identical without doing a full textual comparison.
The friendly folks at Microsoft have even been kind enough to include a "ToHashCode()" method in the .NET framework, but in this challenge I kindly ask you to ignore that.
The challenge is to code your own method that returns an integer hashcode for any string, so that two identical strings will have the same hashcode and that probability of two different strings sharing the same fingerprint is as small as possible.
So, write a method with the signature: static int MakeHash(string s); in C# and post it as a comment here.
Any posts that use ToHashCode(), MD5, or any other build-in hashing mechanism is disqualified along with posts that is almost identical to prior entries.
Post before friday and I'll make comparisons between the submissions on two different parameters:

• Performance
• Duplicate Hashcodes for non-identical strings

Good luck, Gentlemen!