I'll echo what Luke said: the grainy B&W in-camera filter is quite nice. I also rather like the effect of the 'PinHole' camera (which features vignetting and slightly exaggerated colors). That said, the camera also produces nice digital negatives which are very malleable and processable (is that an actual adjective? probably not...). Most of the photos I've posted were processed in a combination of Lightroom and one or two presets, and then tweaked a little (randomly, to try to get closer to what I was looking for). I've also played around with Nik's Analog Pro app, which piggy-backs on LR but is a standalone app itself, and which has a number of powerful and, to me, interesting, tools and presets, including a number of black & white ones. Nik's Silver Efex is also rather fun; and I often use some of the inexpensive but fascinating monochrome presets from X-Equals. And last but not least, the legendary contemporary street photographer Eric Kim has a number of 'free' LR presets that can be downloaded at various sites, some of which are quite cool. I used (and tweaked) one of his monochrome presets for the photo I posted earlier in this thread ('Nikon Man') of my friend Bob shooting with his Nikon.
All in all, the E-P1 + 17mm is an interesting combo. Not quite as wide as the Coolpix A's 28mm equivalent, but an interesting focal length to see the world through.