I know that
www.collectorz.com makes a photo collection software but I am not familiar with how it works or how good. I can vouch for their movie collections software though, it is awesome.
As for Picasa can't you tag a photo thus allowing you to enter whatever tags you want, then when you search for that tag it would pull up anything with that tag? You could date something, and tag it with Mom so if you search for either of those that image would come up.