I have had a lot of fun with JServe, I have also used Jrun by Allaire and enjoyed that a bit.
Jrun has a cost to it for the enterprise edition, but it is pretty cheap I believe 2k for the system, it is a little easier to customize that JServe from apache, makes servlet chaining a snap...
However if you are willing to put in a little extra time (30 min to an hour) you can get JServe to do the exact same things.
I would also tend to disagree with the you get what you pay for aditude when it comes to servers, and server products. Apache servers are free, they do an awsome job, and kick the shit out of the expensive IIS products. The open source products are also by far more customizable than their closed source $$$ intensive counter parts, as well as recieve more input on bug notification, and bug fixes.
If you are looking for a network reaching solution then I would say the apache foundation solutions are what you are looking for, because I do not know how anyone could justify pay that kind of money for software, that does the same thing as software provided by an open-source vendor. Shit, for 5-30k you could hire someone and get a up to 8 months worth of labor out of them on just making JServe fit the companies needs, and have by far a more useful product, just because the product was completely customized for your own use.
-mage-