Hmm... This list may get rather long...
A park bench across from the palace in London (until the royal gaurd came over to see what we were doing).

The Tube on the way back to the hotel after getting interupted by the royal gaurd.
A bathroom while there were people waiting in line during a party.
A park bench at the university on a walking path used very often.
A baseball feild w/ photo session (Sorry, wife doesn't want me to post).
A hotel room with ~15 people sharing the room sleeping.
Driving VERY fast.
Side of the road completely naked in the freezing cold while cars drove by.
Window over looking New York New York in Vegas.

3rd floor window with ex's head sticking out watching people walking by.
Many other open window type deals.
Church parking lot.
Various parks.
On the beach (sand =/= fun!!!)
Her parent's hottub while they were home and awake.
In a hottub while being interupted by other people at a party but not getting caught.
Common room of a dorm hall (well light and always active).
Kitchen of a dorm hall.
Post room of a dorm hall.
Alleyway.
Stairway.
In the closet. (har har)
On the hood of the car.
The backyard (apartments chain link fence)
Places I have yet to but will:
Mile High Club (airplane bathroom).
Movie theater.
Bathroom at a gas station I saw in the mid west named "Kum & Go" We tried at the time, but it was occupied.
Library, very loudly.
Boss' desk.
Also taking suggestions..
