Since the inline spellchecker landed I have steadily been adding words to my personal dictionary. Being a programmer, and using all the jargon in my emails, that's _a lot_ of words already. I just tried looking up one of those words in the personal dictionary window, and was greeted with a really tiny dialog. It would be very good to make this resizable so that - when needed - you can get a better overview of all the list and more swiftly find the one you're looking for.
I agree, it'd be useful, not that I maintain a large personal dictionary as it doesn't carry over on a migration.