Most of my paper is now scanned - I think I have two boxes left in my garden shed. I don't bother with OCR because search doesn't help me when I don't know what to search for (e.g. invoice for a jumper I bought in 2010 - fashion labels rarely call their jumpers jumper).
And so I rely on meta data. There's not much out there in terms of open-source tagging software, and even less in terms of an open tagging approach. I ended up with tagspaces, which is a web app packaged up as a native app. The approach to tagging is good (tags appended to file name), but the app is abysmally poor. Slow - waiting up to 30 seconds for a pop-up menu to appear. It assumes tag-based searches work in only one way.
The intent is to write some native apps to solve my biggest problems. For now I'm still trying to clear the backlog of un-scanned paper docs (not going to get this done for me, because privacy). I tag important stuff, like employment contracts, mortgage agreements, passports and birth certificates...
Hope to have everything done by the time I cash in my chips. Might make for a useful dataset for someone somewhere some day.