For personal uses Lightroom is likely as advanced as you will ever need. You'll be surprised what it can do. People tend to hate the Lightroom catalog concept, but that's what makes very advanced file management possible.
For a larger number of users, you're looking at pro level DAM software at a whole other cost regime. At work we use something called Fotoware, which runs off a dedicated server and allows users to search by any parameter known to man. I'm the main administrator for this (since it's basically filled with my images), so I happen to know that it cost us roughly $25.000 just to get up and running, plus a yearly "maintenance fee" covering upgrades and technical support.
Yeah, and people think Photoshop is "expensive"... 😉
Very nice, Stephen. I'll bookmark that. Consistent and standardized search phrases is essential, and to arrive at that, you need to build an "architecture" in your head first. Establishing the rules, as it were. That link contains some very useful tips.