3 guppies would work, if they were all male. If you wanted some fry you could get 1m and 2f. Keep in mind, though, that that is about 30 fry per month, per female and they do eat their young.
The smallest tank I'd ever put a dwarf gourami in is a 15g tank. They like to live in pairs/groups, and they are pretty sensitive to water quality, they just can't live in a 5 gallon tank.
Personally, I don't support the trade of Glowfish (which are Zebra Danios injected with Jellyfish DNA), but I would never want to see any in a tank smaller than 36" long (I think a 30g would match that description). They are SUPER active and without enough swimming room, they wont be able to gather the proper amount of oxygen with there gills to support their metabolisms. Zebra Danios (and Glowfish) also require a group of at least 6.
If you get cories, don't go below 3. IMO, they really need 5 for one species or 3 of each for multiple species minimum. I wouldn't even include cories in a 5g tank, though.
Go with some guppies! I reciently got 1 male and 2 female guppy and I love them! The male's name is Washington.
(Washington) http://i1237.photobucket.com/albums/...h/DSCN3087.jpg http://i1237.photobucket.com/albums/...h/DSCN3084.jpg
I will probably upgrade the gupps to a 10g soon.