I have a lapdesk for my notebooks. I saw it at Barnes and Noble. It's basically a padded plastic table--and it works well to keep ventilation good and cool. The MacFeet look interesting but hard to support unless its on a table.
That's when I would use it... on a desk at work, at the library, at home, etc.
I don't want to lug around a lapdesk, so that option is out for me. Besides, it's convenient to have when taking the laptop from place to place. Just flip them open when you need them.
Right now, I just prop up the rear of the laptop with something (e.g. book, altoids tin, etc.) but it's not always stable so I'm looking for a better solution.
I prefer the podium pad. The feet are cool. I do like them, but the podium pad does the same thing and actually keeps in off the table by a quarter inch or so. An intern spilled his soda around my (then new) powerbook years ago the day after I bought the pad and we just watched the orange liquid surround the podium pad and not a drop got on the mac. I just stared at him with a smile because I knew he was horrified and relieved at the same time. Was a good lesson learned without learning the REAL hard way.