You can reformat your existing Gmail address by inserting dots (periods) anywhere within your Gmail username. The Gmail Help pages explain:
Because Gmail doesn't recognize dots as characters within usernames, adding or removing dots from a Gmail address won't change the actual destination address. Messages sent to [email protected] and [email protected] are all delivered to your Inbox, and only yours.
We've talked about how you can create unlimited Gmail addresses using the "+" sign before - a technique lots of people use to automatically filter messages. Periods could be used for the same purpose. (Note that Google Apps for Your Domain does NOT ignore dots in addresses.) Thanks, 3xSteve!