Mine was pretty much the same way - I let it leak for a long time before I decided to fix it. The front of the engine was absolutely filthy, and I spent a lot of time cleaning up the parts (it was leaking from *both* the front cover and the tensioner bracket bolt).

If it turns out to be the tensioner bolt, you'll have to take the fan and the belt off to get at the bracket, which then needs to come out to properly clean the area around the hole (I didn't do this very well a couple years back, hence the leak). You might want to check and see what condition the belt tensioner is in before you do this, if its bad you'll need to get a new one before bolting everything back up.