Personally, I use Coppermine Photo Gallery which is PHP-based. It requires a database (I'm using MySQL) but there are other alternatives which use flat file based data sources.
Coppermine allows users to create accounts, upload their own photos and comment and vote on photos. There is a bunch of advanced features which I haven't dug into as yet. The main website has a complete list of functionality.
Obviously there are also other options for ASP.net solutions also. What web server are you hosting on?
Coppermine's Requirements are:
- Any webserver, Apache recommended (Coppermine has been reported to work with Apache, Microsoft Internet Information Server (IIS), Roxen WebServer, Abyss, JanaServer)
- PHP 4.2.0 or better
- GD lib or Image Magick
- mySQL 3.23.23 or better (4.x recommended). Don't confuse the client api version (which is shown in phpinfo) with the mySQL version!
Oh plus, Coppermine is free software and is being released under the GNU GPL license.
[ http://coppermine-gallery.net/ ]