SpyFu were kind enough to send me some invite codes a few days ago to give out. Here's a few codes you can use to receive 50% off the current subscription rate. These are three codes, and once one is used it is no longer available.
Invite Code 1: BZ8U-CJXX1
Invite Code 2: PESX-YJKM2
Invite Code 3: 4UIQ-Y5ZP3
SpyFu is a service that helps you track how web sites rank in the search engines, and how they compare to other sites in similar categories and search terms.