At $WORK I'm still doling away at my Mason-powered webapp, that keeps track of interesting biological sequences.
Lately I have been AJAXifying things with the help of Prototype, http://prototype.conio.net. This works out quite nicely. For the user it makes the interaction more fluent. For the programming part, I experienced that it makes the seperation of content and actions more natural. I have to admit though, that I have no proper MVC setup yet.
For effects I use http://script.aculo.us. I'm quite fond of the autocompleter. I use it to let the user choose for the NCBI taxonomy database
The next think to look for is a consistent set of widgets, preferably based on Prototype. Perhaps Rico, http://openrico.org
