There are apparently 6 species of archerfish known. Not all of them are brackish, and not all of them are avaliable in the hobby.
The ones you have, Toxotes jaculatrix, is by far the most commonly imported species. Next to that is T. chatareus, which can sometimes be imported with T. jaculatrix at times. I have both these species in my tank, and they live happily together.
Slightly less common is the smallscale Archerfish, T. microlepis. I've never kept them but most sources say that they're actually a freshwater species, and may only tolerate slighly brackish.
A rather rare import is the primitive archerfish - T. lorentzi. I've seen a handful of guys on this forum with them. Very nice looking fish, but freshwater as well.
The other 2 archerfish species hardly, if ever, make an appearance in fish stores.