I use Ramaze, a beautiful Ruby web framework. Couple that with M4DBI, a Ruby ORM built on top of Ruby DBI. For JS work, jQuery wherever possible (I avoid plain JS like the plague!). PostgreSQL is my choice of database.
I have experience with Rails, mod_ruby, JDBC, ODBC, PHP, and "plain" sites (HTML, CSS, JS), but I am quite happy with the above-listed software for my web app stack.
I believe Ramaze can run under JRuby.
