I've been running my Calibre library on the web for a few months but using Dropbox as a host for the files. Gets rid of all the problems of running your own server.
So You
Open a Dropbox account
Create (or move) your Calibre library into your Dropbox Public folder (in my case My Documents/My Dropbox/Public/Library
Use Calibre2opds (v2.3) to create your catalog (within the Dropbox Library)
The only special option I selected was 'Browse by Cover'
Then Just use the Dropbox link for the file _catalog/catalog.html to access your library from any device with internet access in the world.
Viewed with web browser
Viewed on Nook