Ajax is a thing I'd like to play with more:

   http://www.onlamp.com/pub/a/onlamp/2005/06/09/rails_ajax.html

By exploiting a Javascript function called XMLHttpRequest it is
possible to create Web pages that seem more like desktop applications.
By not forcing the user to go from page to page to page it is possible
to keep the attention of users longer as well as provide a more
interactive experience. The link above describes this in more detail
and points to a number of Javascript libraries for a number of
languages enabling you to write such applications more easily.

FYI.

--
Eric Morgan