I know that there are certain fish that are beneficial to a tank, for example: certain wrasses, tangs, and gobies.

What other fish are beneficial like the above?

It really depends on what benefit you're looking for. Algae control, aptasia control, sandbed maintenence, detritus cleanup, fish cleaning, etc.

Tell us what you're looking to get done, and we can give you some ideas.

A lawnmower blenny or Rainfordi goby can be very beneficial if you are having algae problems.