Yeah, I remember looking all over for an open source GUID function. One that is standard compliant.
Maybe I don't understand what you are trying to achieve but I doubt it is a good idea to start flooding the filesystem with GUIDs, and it isn't really something that should be promoted.
You might be able to achieve the same effect with a random string creation routine, and there are plenty of those around for various languages. You can achieve similar effects using time stamping down to the millisecond. Combine the two and you'll be fairly sure to have a unique string. Change it to generate a hex string and you might get something like a GUID.