I'm hoping to avoid building this if it already exists. Does anyone know of a plugin for Ruby on Rails that will generate a screenshot of a web site? Thanks in advance to anyone who can help me find one.
This is not a plugin, but I found this snippet which is using an external site to do what you want (I think.). I didn't test it though.
As far as I am aware you need a server with a desktop (eg. Gnome, X11, KDE) and a web browser with thumbnail capabilities installed (eg. webkit and CutyCapt). Of course this is not usual for a Linux server.
I have used the service suggested by Soufiane using code based on Peter Coopers snippet and it works very well.
Generating website thumbnails would require significant server resources and some sort of background process and job queue so using a web thumbnail generation service might be a better alternative to generating your own.
Yes there is a wonderful solution:
It has an great API and there are some Ruby Wrappers (i.e. http://github.com/simplificator/rwebthumb)
It allows you to process 100 thumbnails a month, if you need more the price for credits is very generous if you ask me.