Can you start us off

What kinds of fish do you like...?
Would you preffer a peaceful community set-up or a highly active or colorful set-up or are you into single-fish tanks or cichlid tanks or maybe biotopes?
If it were me, I'd naturaly base my choices around gouramies... I'd get myself a trio of pearl gouramies, 4 dwarf chained loaches and a school of 6 harlequin rasboras. Simply plant it all up and you have a very peaceful, natural-looking tank.
Alternatively, I might have considered a more active and even more colorful combination - perhaps a trio of swordtails, a school of 6 praecox rainbowfish and 4 zebra loaches. You could replace the swords with a trio of cherry barbs or with a trio of american-flag fish if you preffer.
If you want something a little more boisterous, 8 tiger barbs and a flying fox might be the way to go.
If you like cichlids, maybe a peaceful german blue/gld ram pair OR a slightly more boisterous bolivian ram pair OR a krib/pulcher pair plus a school of, say, 7 checker barbs and, maybe, a bristlenose plec. Add a ceramic pot, a scattering of plants and some rockwork...
You could also try going for a realy 'weird' tank but using relatively common species - maybe a school of 6-8 blind cave tetras, 4 or so kuhli loaches and a bristlenose.
You can also go the 'tiny' route - myer's hatchetfish for the top, endler's livebearers, pygmy cories and spotted rasboras. maybe a trio of sparkling gouramies OR honey gouramies as well. You could keep a total of about 25 fish if you went for these tiny species - so plenty of activity + quite bit of color.
There are so many options for a 27 gallon... Like I said to begin with, if you could give some indication of what you're looking for, it would be very helpful. Also, make sure you fishless cycle the tank in question BEFORE adding fish.