I tried the celery regrowth method. Didn't have a good enough light source though so stopped trying.
My sister just told me yesterday that she found her geraniums from last year were still alive after being put into a paper bag last Fall and left in the basement till just a couple of days ago. I saw them and they're growing again. As I love geraniums I'm going to try to save mine this Fall and see if I can get them to grow again next Spring. You need to shake as much dirt off the roots as possible before placing them into a paper bag. Don't want to put them where they might freeze either. I'd heard of this before but never tried it myself.