>> Which web host providers will allow me to install it?
It's just a tomcat servlet container. The big Linux providers (Godaddy etc) do want you to use vps for Tomcat, but it's where Joomla was a few years ago with smaller providers offering great deals to grab market share. Prices are as little as $2.85/month for one site or $6 for multiple sites and a private JVM. Both deals include the database, email and other addons you expect from a hosting plan these days. Tomcat also works with IIS but I can't say whether the Wintel providers would be as competitive.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
