A first prime lens suggestion?

What lens or lenses would you suggest for my first PRIME lens for my E-PL2?  I'd like to purchase/have a lens that is specific to my PEN camera and not duplicated in my DSLR gear.

So a fast prime, with it being used on the PEN quite a bit.  So needs to be a focal length usable for a lot of general applications.  I'm thinking probably in the 20mm to 25mm range (40mm to 50mm as in 35mm terms).  Do any specific lenses immediately jump to the top of your suggested list?  Obviously Olympus would be preferred, but Panasonic would be fine.  And are there other lenses manufacturers making credible m4/3rds lenses now?  Anything to consider there?

In the short time spent with my E-PL2 (about a week now), I'm really liking the IQ results with my kit lenses, and really like the size, weight, and general handling of the camera.