Didn’t you remember this cool feature in an old ICQ version, which enabled you to add floating contacts? And you missed it in the newer versions?

“Icon on Top (On)” - You can use this option with specific users on your Contact List, so that their names always appear on your screen even when the ICQ program is minimized. 

Well, you can achieve a similar result, by using desktop shortcuts. :)

Therefore simply rightclick on your desktop. A context menu will open, letting you choose from various options. Here, choose New -> Shortcut.

A window will open letting you type in the location for the shortcut to lead to. Type in:

icq:send_message?uin=[your contact's ICQ#]

For the [your contacts ICQ#] you can type in a ICQ number, an AOL screenname, or even a phone number with the full country code.

When you’re done, click Next. You will now be asked for a name for your new shortcut. Here, type in your contacts name on your contact list, or if you want, even something completely different. You should use your contacts nickname, but it really doesn’t matter, it’s your choice, you know. ;)

When you’re done, click Finish.

Now, you’ve got a working shortcut on your desktop, which will, if you double click it, open the message window for the choosen contact. But, you know, this default web shortcut icon is not that good. So now, rightclick on your new shortcut and select Properties. A window will open, letting you choose different things. Here, click on Change Icon, and another window will open. Maybe a confirmation window will pop up, telling you an icon could not be found. Ignore it in this case and simply click OK.

Now we have this window, where we can choose from various default Windows icons, but that’s not really what we want. There is an input bar, where we will type in:

C:\Program Files\ICQ6\services\icqApp\ver1\theme\IMAGES\Common\IcqIcons\WindowsIcons\win-icon-message.png

Then we click on OK.

Note: This will only work with ICQ6. If you haven’t installed ICQ into C:\Program Files\ICQ6\ or if you are using a localized version of Windows XP, this directory might be different. You will have to replace that part of the file path with the path you have choosen while installing ICQ.

http://www.dorianmuthig.com/blog/2008/03/17/floating-icq-contacts/