Never heard of them or maybe I have - it's such a generic name who knows. There are a fair number of travel agents that specialize in dive travel, and many dive shops do some of this as well.
Personally, I rarely use travel agents - when I do, it's because they can get me some discount I can't get on my own, or the logistics are easier for them in certain cases. For something like your garden variety dive trip from the US to the Caribbean, it's often simpler to do it yourself. If I do use an agent, I still do all my own research and tell them exactly what I want. For various reasons I would never rely on one to pick places or dive ops, you really can't just put it all in their hands and trust they will suggest the best ideas for you.
Where are you, and do you have any idea where you are thinking of going? When? What kind of budget? If you give some more idea of what you're looking for people on this board will probably have suggestions of good places to go.
There's much to be said for doing the academics and pool work at home, then doing your open water checkout dives at your destination. It's called a open water referral and is quite common. This will give you more time to do more diving on your trip, which is the way you really solidify what you learned in class and get better at it.
Are you doing this by yourself? If so (or even if not) you might want to look around for a local dive shop that plans group trips and go on something like that. Usually it would be no problem to arrange checkout dives on a trip like that, whether with the dive op where you're going, or with an instructor who might be accompanying the group.