Ive built quite a few 'water rockets', which are essentially a 2 liter bottle with fins. Fill partially with water, add 80+/- psi, and release. They are surprisingly powerful and with a little design they can approach 300'. I believe the record is over 1000' which incidentally was not made with a pop bottle but a florescent light tube cover. Any web search will yield results... here's a great site.
http://ourworld.compuserve.com/homep...ocketIndex.htm

More on the RC realm, here's a guy that built one as a glider. Power up, glide down.
http://www.charlesriverrc.org/media/...terrocket2.htm