theres a hundred ways to do it and each one will give you a different effect. one that im fond of is with digital delay
Thanks man, do you think you could expand a little on the different methods? With digital delay is it a matter of cranking/tweaking the feedback?
^ yup, i have boss br8 with tweakable digital delay. one thing i like is to record something, like a percussive hit/rake on my guitar strings at say 1000 ms delay with the feedback on 100. then while its delaying tweak the delay time down to 100 ms then up to 750 then down to 26 and so on and eventually stop (usually at around 600 - 900 ms) and it can create a weird percussive sound.

another fun thing is to mess with the chorus and flanger and tweak those effects and use your guitars volume knob, throw in a wah pedal or a ring mod and no one will ever know the signal came from a guitar
check out the robert fripp vids. he calls them "soundscapes".
ZeGuitarist's sister is hawt.