To use Sensr.net you need a network camera that supports FTP. (Almost all most network cameras support FTP these days). Using FTP is the easiest way to get images out of your camera and onto the Sensr.net site and doesn't require you to configure your firewall or memorize IP addresses.
Though this list is not all inclusive, the following network cameras are proven to work well with Sensr.net:
Loftek CXS 2200
Loftek CXS 3200