one question I have is why buy something when you don't know
if it would be good for you or not?
use that little flash on your camera for awhile. when you start feeling
the limitations of that small built-in pop-up flash you'd be in a better
position to know what flash you need to buy.
to help you out here's a few reasons on why to get a hotshoe flash...
- it's more powerful... and usually the higher the model number the farther you can throw light in the distance (tip: learn and understand guide numbers)
- the built-in pop-up flash has a fail safe device to protect your camera. if you fire that small flash continuously even at 1 shot every 1~2 seconds your camera will freeze to let the unit cool down. in my canon 40D it can take a minute or more. imagine that happening during a fast paced fashion show. a hotshoe flash can better handle the stress.
- it will also have it's own power source helping you save on precious camera battery.
- the closer your flash is to the lens the more chance of getting "red eye"

- and direct straight-on light is rarely very flattering. a flash with a tilt-swivel head can help direct the light elsewhere either by bounce or triggering it off-camera. see these vids: Nissin Digital Flash: Di622 MARK II INTRODUCTION
sunpak and nissin are trusted and proven 3rd party flash manufacturers and offer high performance models at the cost of... and sometimes for half the price of the branded entry level models. yongnuo I think is a new player in the market but seems to be giving good value for your money as well.