Use Gmail Generate Unlimited E-mail Addresses

Gmail has an interesting quirk where you can add a plus sign (+) after your Gmail address, and it'll still get to your inbox. It's called plus-addressing, and it essentially gives you an unlimited number of e-mail addresses to play with. Here's how it works: say your address is twomadgeeks@gmail.com, and you want to automatically label all tech e-mails. Add a plus sign and a phrase to make it twomadgeeks+tech@gmail.com and set up a filter to label it tech (to access your filters go to Settings->Filters and create a filter for messages addressed to twomadgeeks+tech@gmail.com. Then add the label tech).
http://21st.blogspot.com/2006/09/use-gmail-generate-unlimited-e-mail.html