Mirabilis's
ICQ is (at the risk of argument) the oldest, biggest and best
instant messaging service, which spread in the early days by word of mouth, and was eventually purchased by the
AOL Time Warner behemoth.
As great and useful (and secure as a wet paper bag) as the technology is, there are some minor problems with the client software.
Clearly, Mirabilis's developers (or chimps, as I like to call them) are the biggest collection of Visual Basic-reared jackasses ever to draw breath. Their client software is crammed with useless features*, and has an incredibly ugly and unintuitive interface.
An interface that, for example, doesn't use the right-click for anything apart from a message telling you to use the other button. That prints user details in grey on a grey background (and doesn't let you highlight them, or change the colours). That resizes and repositions itself stupidly whenever an OpenGL or Direct3D application does a resolution switch. That features banner ads in places where other clients don't have places. And features a barrage of crappy sounds that have to be turned off or erased to maintain your sanity.
And don't get me started on the options dialog ("look how many controls we can fit on a form!"). Why don't AOL sack these buffoons and let those fine fellows at Nullsoft (whose souls... err, company they also own) do their l33t interface-fu on it?
Thankfully, there are many alternatives available to the ICQ junkie, such as the slinky MICQ, or the highly competent Trillian.
*the SMS function is pretty cool though.