The good folks at Nookdevs have hacked the latest Nook firmware. (I'm beginning to think B&N doesn't care.) The Nookdev v1.4 firmware comes with quite a few apps preinstalled:
You can find out more here. The usual warnings and cautions apply.
But I'm not so sure that you should get this firmware. I've seen a couple reports at MobileRead Forums about v1.4. Both users have encountered bugs. You might want to wait and see if more complaints are reported.
Would you like to do more with your Nook like run other apps, download RSS feeds and web content, and in general use your Nook like the web tablet it could be? Then you should visit the Nookdev site, and see what they've done.