Steven, there's a general guideline you can use when judging how many fish you can keep in a tank. It states that for every gallon of water, you can have one inch of ADULT fish. The 'adult' part means you have to consider adult sizes.
Having said that, the guideline doesn't take into acount behaviour or schooling requirements etc. Also, even if a fish is 10", you can't realisticly keep it in a 10 gallon as it'll hardly be able to move around
For example, cichlids tend to be highly aggressive and won't work in a community set-up. Most also grow far too big for a 10 gallon even if they are udner 10" as they tend to be highly territorial and need tanks of at least 30 gallons.
Swordtails are far too active for a 10 gallon tank and also grow somewhat large for one. As a general guideline, avoid any fish that grow over 3" when planning inhabitants for a 10 gallon.
Guppies are fine and will work with a dwarf gourami. Having said that, make sure your guppies are either all male or kept in a ratio of 2 or more females per male.
If youw ant a dwarf gourami, stick to only 1 male. females are duller and can also be quite hard to find as many LFSs won't stock them. Males do well in peaceful community set-ups but, because, like most gouramies, they are territorial, they need at least 10 gallons per gourami to set up a territory in.
So to summarize, 1 male dwarf gourami and a handful of guppies (say 4 to reduce aggression - with only 2, one may bully the other) and a couple of dwarf frogs, your tank is actualy just about fully stocked. You may want to add another couple of fish under 2" as well - but aim for fish that spend most time near the bottom of the tank or in the middle. Perhaps get 2-3 pygmy cory catfish (ask your LFS to order some in if they don't already have some).
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