This is a system that will eventually be used to control access to various rooms and machines at TechShop. It uses an Arduino, Ethernet shield, and RFID reader. There's a bonus Seeeduino waving an RFID card in front of the reader for reliability testing.
Photo below, but I've also got a video here: http://www.flickr.com/photos/macetech/3393654907
used to control access to various rooms and machines at TechShop.
I think I just became jealous of you. 
--Phil.
Very nice.
Have you heard of DoorD? I think it's more the back-end access control stuff rather than the RFID hardware, but it's used by The Hub in London for their door access and is open source, so it could be a good fit with your hardware.
See GitHub - derfred/doord: Networked based door access control for more details.
Hi.
Very nice...
Would you share the code with us?
Thomas