NINA.chat is now giving free AIM access
After such a long time, the NINA.chat people have opened registrations for AIM for free (previously required a donation of 2 or 4 USD). If you don't know what NINA is, it's basically a project that tries to revive old instant messaging programs like the one I mentioned here, as well as ICQ, Yahoo Messenger, among others.
If you are interested, create an account on https://nina.chat/register/ (if you already have a Escargot MSN account you can skip this step) and get your favorite AIM client version at https://nina.chat/download/aim/lang/en/. In my case I've chosen version 4.7 because version 5 onwards comes with AOL crap that is installed by default (such as that classic "Free AOL Internet" shortcut on the desktop). If those AOL ads on the client annoys you I recommend you also download DeadAIM at http://www.oldversion.com/windows/deadaim/ (use version 1.0.2 if you are using AIM 4.x) which removes them completely from the program.
Have fun and enjoy the nostalgia!