I have an 05 corolla with a CD changer (no tape adapter) and have been looking into those options as well. Here is some of what I found:

There are lots of adapters out there that might be able to connect to the back of your radio (like the BWM-ipod connections).

http://www.ipod2car.com
http://www.pac-audio.com (bottom of page, less brand name)
Both the ipod2car and pac systems are essentially the same boxes and work the same way you hook the adapter to your car stereo (installation required). If you have a CD changer that came with your car you might or might not lose the ability to use that changer (you should read the faq section in ipod2car, i found that most helpful). The adapters are around US$189 and you need to purchase a compatible adapter cable as well (at least you do for PAC)

http://www.alpine-usa.com/driveyouripod/
There is a catch for the alpine system. You have to have a compatible alpine head. This can get expensive as you might have to replace your existing car stereo head. The heads start at a couple hundred and THEN you purchase the device that connects your ipod for another US$100. I don't know if that includes installation.

Good Luck! there are a lot of options and they can be expensive.