I just installed Cooliris on my ning. It's a real cool looking 3D gallery that will spice up your network.
This is how it looks like on my network:
As you can see people can add your gallery to facebook and twitter also or expand it to their big screen if they want.
See it in action: http://inventorwizard.ning.com/
or check out ther website and create your own...it's free and I love it: http://www.cooliris.com/yoursite/express/
Before I forget, youtube or facebook stuff can also be added in it. I'm sure you'll find it easy to configer it.
Maybe on remark for Picasa is that your gallery name may NOT include spaces in the name of the gallery. For instance: inventorwizard is allowed but not inventor wizard. Cooliris will not be able to find your gallery if you don't take this into account!