You can connect your electric guitar to your computer soundcard line or mic in with a hacked together cable, and use any one of many programs to get every effect
you could get from any effects box or any amp ever made just about.
Native Instruments Guitar Rig 3 is what I'm using with a realtek onboard sound chip (one of the new decent ones)
(there are tricks to getting it set up right for quick and accurate digital effects, but it's all well documented on the net)
Software can be found at a pretty good discount online if you shop around but is expensive as hell in a store.
I've got a strat copy that I got off ebay and was local for $!8, didn't need a card to pay for that... I also have one of the Epiphone Bob Marley limited edition guitars for that Gibson sound.
There are also usb guitars that come with very limited versions of sound fx software...not sure if they're any good though.
Anyway, just a thought....
You can also just plug one directly into your computer speakers inputs if you can get by without effects.
If only I had a clue of how to play them, I need to overcome my ADD type farting around and actually use the things right one of these days.
Oh well, they're fun to play with and look real cool on my wall.