Ok, it could be argued that every book from this site saves you money since you aren't buying them from a bookstore. However, here's a few that go a bit beyond that.

365 Ways to Save Money :: Lucy H. Hedrick
ISBN-13: 9780688127015 - ISBN-10: 0688127010

52 Ways to Stretch a Buck :: Kenny Luck
ISBN-13: 9780840796554 - ISBN-10: 0840796552

Money Smarts :: Boardroom Reports, Inc.
ISBN-13: 38963 - ISBN-10:

Save Your Business a Bundle: 202 Ways to Cut Costs & Boost Profits Companies :: Daniel Kehrer
ISBN-13: 9780671788933 - ISBN-10: 0671788930

The Unoffcial Business Traveler's Pocket Guide: 249 Tips Even the Best Business Traveler May Not Know :: Christopher J. McGinnis
ISBN-13: 9780070453807 - ISBN-10: 0070453802

All 5 of the books are on my shelf. Most are also available from other people. These books are great for anyone who doesn't have enough money.