While it isn't specifically a penis enlargement site, http://www.the-penis.com has a ton of information you might want to peruse concerning the procedures out there.
The only 'natural' technique that I know of is where you get your penis to a state of half-erection and gently but firmly squeeze it from base to tip in a sort of 'milking' action. On the site I gave you it lists it as an ancient Arabian techinique called 'jelqing'. From what I know, you have to do it for about 20 minutes a day, for many months or even over a year. I can't confirm whether it works (I haven't tried it) but no doubt, it's most likely the safest procedure out there.
