Removing glue form glass jars

[unroolykitty.livejournal.com]

Quick question--is there an easier way to remove the labeling glue from glass jars? I've been scrubbing on my old mayo and mustard jars all afternoon and I thought maybe someone out there knew of something that could get the glue off more easily. I know there's goo-gone, but is there something more 'homemade'?
thanks everybody!