Argh, sorry about that. It looks like you have to click on the link from the main page. Go
here. The link to the Bart skateboarding one is under Bart Simpson Pictures, 3rd column, middle of the list, between "Bart looking hopeful" and "Bart with spray paint".
The Homer and Marge Dancing is under Simpsons Family Pictures, 3rd column, 2nd from the top.