I found the "astrophotography" here: www.lomography.com/magazine/tipster/2011/11/08/astrophotogr…
Got some nice results with this kind of double exposures :-)
(I've tried other computer screen pictures before, too. But they doesn't really work well. Probably too bright.)
virginianin, jackpumpkinhead, saraess, chloeackers, clarinetmonster, robotto_dawad, mouthwork, lomalex, melonhead, saidseni & dobendan.
I've just done this too. Haven't finished the roll of film yet so hopefully they'll turn out just as good as yours :) x