if you are computer familiar at all, you can easily use a PC with X10 Equipment to handle this.
X10 has Dimmer settings built in, and with those blue party bulbs you can use one of the X-10 Light devices easily for it.
you can get a full setup to work with your PC for $50 bucks as startup kits that contain everything you need to work with x-10
try
www.x10.com and
www.smarthome.com
you will need a Firecracker, which is the actual device that connects from your PC to your x10 stuff, and then some lamp modules. X-10 is really pretty cheap, and even radio shack has x-10 parts.
for software, you can find many apis out there to work with it, there is a very advanced (and free) package for x10 called misterhome, and it has a built in language that you can use to do all of that timer stuff/dimmer settings you are refering too.
I don't know of any simple (the firecracker may come with some) software taht will let you code time/brightness/day of month type of stuff however.
http://misterhouse.net
http://www.x10.com/firecracker/fc_offer_br1ab.htm (this is the kit that will let you start it all-- Does come with software after all)
http://www.smarthome.com