Adium X. It is a very polished app, and operates like a Mac app should. Although I just downloaded and tried Mercury Messenger tonight, and although I'm really impressed that they've got a lot of MSN 7 features (winks, nudges, painting, some games and webcam soon) it is just... ugly. I can't deal with it. When they add webcam, I'll probably end up using Adium X for chatting, and Mercury for webcam, until Adium catches up with their own webcam features. I wish I could use iChat, but I have no AIM friends... Oh, and I use Skype every once a week or so too. Can't wait to see what Skype is cooking up for video and voicemail. Hopefully the Mac version comes out simultaneously and looks as nice as iChat.