I\'m using Trillian right now. It\'s pretty good. Main thing is, it\'s still beta; it\'s on version 0.75. Some of the features (like check mail), don\'t work. It doesn\'t give you alerts (might do a sound, dunno) when you get mail, for example, unless you\'re looking at your buddy list. Ya can\'t set it to minimize your windows when you\'re away, and the message window bar thingies in the staus bar (what the hell are they called?) don\'t flash blue (or any color) when someone sends a message. It doesn\'t do the fonts or colors of MSN or AIM, either. You can choose the font (and maybe color, don\'t feel like checking) for your messages, but it show the entire window in that font, including messages from the other person(s). I really hope hey get that **** handled. Other than that, I like it.
3rd Edit: ICQ never really worked for me, as well. People (actually, I might have only tried it with one person, but it\'s all or none as far as I\'m concerned) said they could read my messages, but there\'s showed up as gibberish. Someone said that regular ICQ does that sometimes, too, though, so I dunno.