What kind of "community" type you have in mind ? community as in fish of all sorts and different origin mixed together or a biotype community ? Biotype communities are a lot more easier to keep and maintain because all the fish share the same water quality parameters and exhibit their behavior in a way that the other fish understand.

Amazonian biotype:

Black Tetras
Pristellas
Head and tail light tetras
Lemon tetras
Neon Tetras
Flame tetras
Blood characin ( too quarrelsome and notorious fin nipper )
Rummy nose tetras
Angels ( Pterophyllum )
Apistogramma cichilds
Corydoras Catfish
Plecostomus ( small exotic ones )
Raphael catfishes

Central american Community:

Jack Dempsey cichilds
Firemouths
Convicts

South East asian community:

Botias ( skip Skunk botias )
Tiger barbs
Gouramies ( if you have tigers skip Colisas )
Rosy barbs
Clown barbs
Rasboras

Malawi or Tanganyka community:

30 gals is too small.

Although 30 gallons seems large, it's not really all that large. I guess it depends on what type of fish you'd like to keep.

Personally, I think 30 gallons is too small for angelfish or some of the larger gouramis (like moonlights). And if you like clown loaches (which should be kept in groups - they like company) they do grow to be rather large - so again, 30 gallons is too small.

The only type of fish I truly feel comfortable keeping in a 29 gallon tank in greater numbers than say, just a handful of medium sized fish, are the slim-bodied fish. Like right now my 29 gallon has guppies in it. Prior to this, I kept neons, cories and a betta.

But as I was exploring the larger bodied fish, I went out and got the 42 gallon, the 55 gallon and then the 75 gallon tank. I think they appreciate the larger space to swim and there is less aggression amongst the fish.

Anyway - that's just my experience!

Assuming you aquarium is a rectangular shape (36" long as apposed to a hex) A good centerpiece fish like an angel or dwarf gourami, then a large school of small tetras, like 20, then some livebearers like platy's or guppy's. This will give you a range of colors as well as different movements. Just a quick thought any combo is nice. If you still like cichlids then the dwarf shell dwellers would be OK in a 30G. Whatever you deside check compatibilityand stock slowly.

for a 30g i agree with dwarf cichlids.
someone recomended a jack dempsey, oh there great fun fish but they get way too big for a 30 gallon. you need at least a 55 gallon for most central american cichlids, and thats usually just housing one adult not a community.
convicts will work, but only a pair, but please be aware convicts are nick named "water rabbits" because they reproduce as quick as a bunny. youll soon end up with hundreds of convicts per year. i dont recomend them.
dwarf cichlids, a few rams or cockatoo's, some tetra's, otto's and thats a pretty nice setup

Yes, that's what I have - 29 gallon planted tank with 2 Blue Rams, 4 Harlequin Rasboras, 2 Apisotgrammas, 1 Swordtail and 1 Platy, the sword and the platy helped me cycle the tank when I first got it and are still with me. I also have 2 Otos and may add an apple snail for my cleanup crew. There are so many options for a 30 gallon tank, have fun!

I have the 30 gallons tank and its filled with 10 Tiger Barbs, 6 Platies, 2 Dwarf Gouramis, and 2 Striped Raphael catfishes. Do not listen to raul_in_mexico on his view about Tiger Barbs and Gouramis. Mine is doing great and its perfectly natural for them to be curious of one another and occasional 1-3 seconds chase between the Tiger Barbs and Gouramis. They do not harm each other. Do not panic if they are more curious within the first few days. I have a short video of my tank, but I record it with my PC Cam at the wrong timing, because most of the fishes are in the back (bedtime). Please note that the lighting in the video was sadly misled on the camera. The lighting is actually perfect and there are no bright reflections. At the end of the video, you will see the one Dwarf Gourami in the upper right corner. I plan to take more videos and pictures as soon I get my professional digital camera out of the pawn shop and compose a webpage of my fish tank and education for people.

Here is a link that might be useful: Click here to see my fish tank!

DO listen to raul_in_mexico.

He knows his fish and understands that the healthiest community tank will contain only fishes found in the same waters in nature.

There are many terrific contributors on this board. With a many years of experience. Raul in Mexico is one of them.

RE: tank size.

If it's a standard 30, it's 36" long and offers better swimming space than a 29, so a school of small fish would do well in it.

Depending upon the strength of the filtration and frequency of water changes, with smaller fish, you can have some fun with just a good sized school of a single species and a smaller one of another, compatible species.

I set up a 30 for a neighbor friend who picked up the tank, hood, lights and stand on a lark at a garage sale, but then couldn't decide what to do with it.

As I'm an Amazon lover, it was an opportunity for me to show off, so....

I planted it, set in some good looking bogwood, 30 Cardinal tetras and 8 Panda corys. The effect of the fish schooling in waves was and remains spectacular and no, it isn't overpopulated.

I also gave her an Emporer 400 and trained her to do a 50% water and media change weekly: 3- 5 gal. buckets out, and in, and fresh charcoal and filter pads- every week.

She loves that tank and the fish have been thriving in it.

She is also now hooked; vists my fish room regularly, and is asking when we next plan to leave town.

Set up a tank and gain a fish sitter. Sneaky old lady aquarist. LOL!