For pixels outside a selected area ... well ... I just make a bigger selection, really. :) Or, sometimes, I use the Distort in Transform ... as in the case of this:

http://www.fotosearch.com/DGV608/1070025/

to this:

http://graphicfantastic.com/galleries/covers/tagsfolly.html

I needed to make a bigger butt, but I had to keep the outline of the dress consistent, so I selected the butt, enlarged it, then used Edit > Transform > Distort to line the top of the butt to the hip and waist. You can do something similar with Liquify, too.

Oh, and I agree about Photoshop being amazing. I've had a lot of fun over the years manipulating photos.