PAIA has a mic preamp kit you can buy (plus schematics are downloadable from their website) http://www.paia.com/
Analog Devices use to make a chip that was specifically designed for use as a mic preamp, the SSM2017. Here is the data sheet http://wwww.ges.cz/sheet/s/ssm2017.pdf I made small battery powered dual mic preamp for my Minidisc recorder from the reference design in the data sheet and it works well. This part is in a bunch of Rane's pro sound products, you can download schematics from their website. http://www.rane.com/
Note: Analog Devices stopped making the SSM2017 two years ago. If you want to try them and can't find any, I stocked up on a tube of 25 of them right as there were being obsoleted and could spare a couple.
If you're looking for a substitute for an SSM2017, check out the THAT 1510. I don't know if they're any easier to get, though. THAT Corp. says samples will be available end of Q2 '02...
The old National Semiconductor apps books from the '70s and '80s had a few balanced mic preamp circuits using a differential pair front end to a chip op amp, which you could improve upon with a few judicious component upgrades. Most of these should be available at the National web site.
Audio amateur recently published an article about a tube mic preamp by Paul Stamler(2/3/4, 2002). It seems to be quite a high-end thing. He also did a two part article in AA in Issues 3 & 4, 1995. This one was about solid state circuits for mic preamps and mixers. Very good article with much discussion about the design decision-making. Stamler is obviously a very knowledgeable guy. Highly recommended reading.
Back issues from Audioxpress.
I want to do one (or a few), but can't yet start since I've got other things underway.