AOLServer was great! I used it for a ton of stuff, the most complex being a marketplace for data. It was almost trivially easy to do fast, maintainable, programmable business logic as part of a complex web site. Having to switch over to the likes of Flask on Apache (not that Flask isn't a decent framework) was a major step back for development, testing and maintenance.
AOLServer was actually bought by AOL; originally it was NaviServer. It was open sourced in 1999 by AOL.
It's a fantastic server, imo, and some of the technology developed for it were eventually brought into the Tcl core (not exactly, but the general approaches) when multi-threading was added. At least, that's my understanding.