Q:

Is there a good flash for which you can get an AC adapter? 

I'm working on a lighting solution for my studio.  All of the lights will be 100% stationary and I'm wondering if there's a way to get flashes that I can just plug into the wall instead of bothering with batteries all the time. 
I've seen projects like this which I'm comfortable experimenting with, but the potential for failure at the wrong time is just too much for my needs.  I want something that's reliable, recycles reasonably quickly ( < 4 seconds) and can be made to run off of AC without modding. 
A full manual flash is fine, I don't need bells and whistles.  I'm planning to set these flashes to a certain setting and forgetting about them. 

A:

Have a look at Alien Bees.  I have 4 of the B800s and they're fun to work with, can be triggered remote, and are very nicely priced.  All manual, but as you say, it's not really an issue.  Anyways, I very much like mine, so they come recommended from me at any rate. :) 
As a side note, they're probably less than a regular hot shoe flash as well given the potential output and other handy features.