dbs - the commands you seek have already been mentioned here

I often use the 'find' construct that itsmeok mentions to find a filename containing a specific piece of text. The (s)locate command Tim mentions is an alternative as well and for content. And the grep command is a very easy way of doing it real time without having to build a database....
I'm really not sure which threads you are looking at.... I imagine there is some other issue at hand, as none of these methods above are in any way obscure, people use them all the time!