I have an HTC Wildfire with what could be the worst battery life in mobile phone history. Part of the problem will be my fault, as I didn’t always drain it before re-charging in the beginning. But now I can’t even get through 12 hours without the battery running down.

The phone is only 9 months old.

Is there anything I can do shy of getting a new battery?

Why not get a new battery? Cheap as the chips on Fleabay. I got one for my Defy and it lasts so much longer. No issues with it.

New batteries cost buttons on eBay

Li-Ion batteries should be prevented from fully discharging if possible. Always discharging fully is not good for battery care and is a common misconception.
The simple fact is that smartphones have poor battery life relative to older phones of a few years ago. Basically the same battery tech but with higher demands (large displays, powerful processors, 3G, wifi, GPS) and the wildfire has a rather small capacity battery at 1300 mAh.

If you want to care for your battery then turn your device off when charging to allow it to reach the correct voltage threshold, only partially charge before usage. The latter increases battery longevity but means usage time between charges is shorter so is of little help for most people.
Turning off unused radios is the easiest thing to do (wifi, Bluetooth, GPS) or disabling background data usage. Unfortunately to make the most of your phone you probably want background data on.
I imagine this post has done little to assist you in your quest for longer battery life 🙁

Switch to only using 2g instead of 3g, I get about 26 hours use from fully charge to dead. Not such a fast data connection but 3g hammers the battery for some reason.

I didn’t always drain it before re-charging in the beginning

Doesn’t make any difference. In fact, full draining should be avoided with li-ion batteries.

Also, try this:

*#*#4636#*#* -> phone information

Switch from WCDMA preferred to GSM auto (PRL).

This will limit the network bands the phone searches to those on the preferred list, thus saving you battery power.

Second, if the battery life is really that bad, you probably have some apps that are draining it by doing frequent data checks etc. Have a look in settings -> about phone -> battery usage and see if anything obvious is at fault.