After reading about WiFi File Explorer - I would mention one of the most used apps on my Android devices (NC and Droid Incredible): The Dropbox app
set up a dropbox account (free at dropbox.com) and then install the app on your NookColor and your desktop computer.
Drop files into your dropbox folder on your computer (apps, ebooks, mp3's, videos); and they automatically get synced your dropbox account on the dropbox server. When you run dropbox on your NC, all of your files are available (to download). I actually set my calibre library up inside my dropbox folder on my desktop, so now my calibre library is available on my NC.
The android app also allows you to share files from your dropbox (email a link for someone to download directly from the dropbox); upload to the dropbox from the app; stream m3ps or videos etc.
As you can probably tell from my glowing review of dropbox, I really like it!
Note: shameless plug: if you aren't a user of dropbox - if you use this link to sign up, I get a little extra free space (hope that's ok to post here):
https://www.dropbox.com/referrals/NT...A5?src=global0