Another albino cory would be good (another three would be best b/c that would make a shoal of six, which is often the recommended minimum), as would be a few more Tiger Barbs (your Gouramies are in danger of having their pectoral fins nipped off if the Tigers don't have enough conspecifics to draw their attention) and a few more Lemon Tetras (they feel more secure in shoals).
I would like to see a pic of the unknown algae eater, or somehow get an ID of it before I say if the tank is ready for Clowns...can you Google these three fish and let me know if any of them is of the type that you have?
"Golden Algae Eater", "Chinese Algae Eater", "Siamese Algae Eater"
If one of these is it, we can work from there. If not, I can throw out some more guesses if given a pic or a description from which I can work.