Definitely check out the tech notes here and browse the forums. There is a wealth of information sitting around here. The practice tests here are good. I also liked free-tests.com as it was good at grilling a lot of the information into you. Mind you though that it is purely for making sure you know the information. It isn't good as a simulation of the exam because the questions are way too short and easy. Transcenders is also a popular one around here as HP mentioned.
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Friends of mine are using the Sybex study guide for 70-270 and rate it very highly. I'm a big fan of Sybex books for other subjects.
Obviously it's different things for different people, but a combination of quality reading and test engines is a good way to start.
Good luck!!
Bsc (hons) Network Computing - 1st Class
WIP: Msc advanced networking