Did you know that the Mac OS X Spotlight feature has the ability to "see" the layer names in Photoshop .psd files? If you have a layer named "timbuktu" in a Photoshop .psd image, and you do a spotlight search for "timbuktu" that image will be found. This could be useful if you misplace a file and for some strange reason you can't recall the filename but you do remember the name of one of the layers. Or, if you need to display all the files in a particular folder to which you've applied a Hue/Saturation adjustment layer.
You can also quickly view the layer names in a .psd file by selecting the file in the Macintosh Finder and choosing File > Get Info.
As an alternative to Spotlight, check out EasyFind. I use this free utility frequently and love it.
Alas, Adobe Bridge, with all of its metadata wonderfulness, can't search for or display Photoshop layer names.