Germán,

For client-side, a fairly heavily modified version of WebClient.

For server-side, I actually started with your port of Aida which I updated (https://github.com/pbella/Cuis-Smalltalk-Aida) and went from there.  Before that I was using Seaside on Pharo but didn't want to deal with getting Unicode support (among other things) into Cuis at the time, which would have been needed for Seaside.  We talked about it on the Cuis list but it sounded like I was pretty much the only one doing web apps at the time and the path of least resistance seemed to be Aida.  Glad I ended up going that route as there are things that I definitely liked better about the Aida approach vs Seaside. (Though both frameworks are good starting points)

Thanks,

Phil