URLs map onto filenames (that's what they originally were), so when wget downloads a URL, it's generally fairly predictable where the contents will be located on disk.
No, that's not what I mean. Let's say you want to look up studies on, say, the effect of dietary sodium on CVD and you have a vague recollection that you scanned a paper on the topic a year or so ago. I understand that if you have the URL of this paper you can easily find it on your disk, but how do you go from, basically, a set of search terms to the right URL?
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.