Cichlids for a 10 gallon

You can happily keep (and breed) a pair of convicts, hrp's or firemouths in that tank, even as they get to their full adult size.

I highly disagree with that. Sure, you might get convicts to breed in a 10gal, because they'll breed in just about anything, but I can't see how they would be "happy" or properly kept in that small of a space.
 
There are a few tanganyikan fish you could keep, I have had a pair of brichardi in a 5 gallon for 4 months, and they are doing great (nice color, very active, growing up just fine)

If space is limited, and a 10 is your only option, I would say that brichardi, or neolamprologus lellupi would be a nice option. They rarely get much larger than 3 inches and a pair of them might give you some fry that you can take to the LFS.
 
try nanos they stay small easy to care for and aren't aggressive.

Archocentrus nanoluteus
 
no nanos stay small under 4in IMO ive never seen one bigger
 
I agree - a small group of shellies is probably the only option here. Even a fully-grown brichardi or leleupi would be a stretch - I saw a beautiful breeding pair of Daffodils once and each adult was at least 4", which I think is too large for a 10, especially given their nature. If you want to see the best cichlid colors and behaviors, you gotta give 'em room to show off! :)
 
AquariaCentral.com