My e-mail address would have to be on the cards.
Correct me if I'm wrong (because I never am, and therefore you'll never have to), but if you saw "email@example.com" on a card, you'd think I was a n00b, wouldn't you? For a start, it's not even my name. It's a lame address with a number in it, and - above all - it's a Yahoo! address. The cardinal sin. So I finally took the plunge, cut my losses and got myself one of these:
innocentlb [dot] blog [at] gmail [dot] com
It's a damn shame that "innocentlb" wasn't available, necessitating the .blog at the end - I wonder which git nicked it, stopping me aligning it with my Twitter and Formspring usernames? Still, it's pretty enough, and it's much better than my old e-mail address. And yes, it works on MSN too. And I'll close my Yahoo! account after a couple of weeks so no spam gets forwarded on.
Oh, and you can add me on MSN if you want, although if you're reading this, I've probably already added you. Try, though. I'm fun to talk to and I have a new address.
I feel so wonderful and just a little bit more geeky for this very small act of defection to Google. And hey, it could be worse...
...I could have switched to an msn.com address.