what are the most common models of Nikon and canon lenses that people are using for these adaptors? Looking to purchase inexpensive one to experiment with and to possibly use with a purchased adapter(not sure which one yet). Thanks

A ton of posts deal with this subject...try the search. I use Canon FD mount lenses. I love the 50mm, the 28mm is good at times, I use the 75mm a fair amount.

for people who have been practice still photography may be 35mm adapter world little bit twisted. Steve, if You have been, then You know that focal lenghts for wide angle (http://en.wikipedia.org/wiki/Wide-angle_lens) is 35mm and lower, for normal (http://en.wikipedia.org/wiki/Normal_lens) around 50mm, for tele (http://en.wikipedia.org/wiki/Telephoto_lens) over 80mm.
In 35mm adapter world You have to often multiple lens original FL value because of smaller target area. If 35mm still photography uses originally 24x36 framesize then 35mm adapters may use smaller areasee - my earlier post (http://www.dvinfo.net/conf/showpost.php?p=521873&postcount=5). So You got completlely new range of lenses: wide angle fl= under 22mm, normal fl= around 31mm and tele fl= over 50mm. Those which are called tele in still photography are mostly here as supertele.

Best picture quality(even when adapter itself performes poorly) You may achieve with teles(in still photography meaning). Mainly because of their uniformal light distribution. But such angle of view is painful(imagine -You shoot with Your camera only zoomed in position). Normal is normal - somewhere in between teles and wides. Using wide ange is most difficult and same time the best test lens for Your 35mm adapter. Because it's very hard to find wide angel lens which has same time very short FL, good light distribution and big enoough max iris size. But don't give up such exists.

Thanks for the reply Frank. The links were very helpful.

I am building one of these DOF machines as seen on this link
http://www.mediachance.com/dvdlab/dof/index5.htm

I have a panasonic GS400 and I am looking for a suitable 35mm lens to go with the machine. I appreciate the responses so far but when I look on the web to purchase a recommended lens, the choices are infinite and I'm not even sure if I'm looking at the lenses that people are talking about on here.

also, can anyone help with the macro-lens side of this machine...which one should I get?

Any help would be appreciated