It's damn cool!
It has a great design, cool effects, no crap like with the regular ICQ, and uses much less resources! A very good piece of software.
And did i mention it has no advertisments?
Mirabilis are saving their own ass.

link

Hmm, i suppose this needs more clarification.
With the rising popularity of Trillian and other free Instant Messaging services, the competition is tougher than ever.
So Mirabilis did the most reasonable thing. SMART MOVE!

I use trillian because MSN is most used in denmark among high-schoolers and ICQ is most used in this community. Futhermore I spend all the time I can at #ha so it's much easier to have an all in one solution.

Yep, Trillian is great.

Easy Message
http://www.easymessage.net/

Easy Message is the all-in-one instant messenger
that provides support for ICQ, MSN, Yahoo and AOL
all at the same time.

The design is similar to MSN Messenger.
I could not find any chat log.
The install file is on about 240 Kb
and the installed program take about 800 Kb
on the harddrive.

I've been using miranda for some time now. It's open-source and people can write their own plugins which I think is great!

http://miranda-icq.sourceforge.net/

My favourite is Jabber. Rival is a very fine client, haven't tried others recently though.

I was just going to post saying abou the same thing. Miranda is really nice.