If you want something less database-like, a little more freestyle, probably closer in spirit to a journal or something...I've been using a program called VoodooPad.
Flying Meat: VoodooPad
Kind of like a scrapbook in that you can write text in it, create tables, paste in pictures, link to webpages...pretty much anything you want to do with it.
For example, my index page is a table of all my 'chids with when I got them, where from, when I last repotted. Each of the plants listed there links to its own page, on which I keep notes and track how it's doing along with cultural info I find on the web, and photos of it. All of the pages can also be put into categories – I categorize my pages by alliance.
Anywho, if you're interested, you should just check out the website b/c I dunno how great a job I'm doing explaining it. The bonus is that you can get a "Lite" version of the program for free (tho I think it would be pretty limiting) and the standard version is pretty cheap at $30. There's also a "Pro" version, but I didn't see needing that version.
Anywho...this program is really great if you want something extremely flexible.