I've been dealing with the issue lately also. Here are a couple thoughts.

I keep only one copy of the fonts organized by foundry—that way, I don't end up with conflicts or accidentally deleting my only copy because I thought I had a duplicate somewhere else. (plus it helps me remember who designed what). In FontExplorer each font can have comments assigned to it. In the comments I'll use adjectives that describe the history, the style, the mood, etc. or add one pertaining to a client. I then create smart sets that use those key words. So if I'm looking for a bold, feminine, sans serif. I can quickly create a set that gets me where I need without endlessly sorting through folders and lists.

I just keep only the bare essentials activated. I keep all foundries organized in a folder and i simply activate the font/foundry i would like to work with in FontXplorer X(Each individual foundry is a collection in my FontXplorer X). I tend to use the Foundry websites a lot to browse through the faces and decide which to use/buy. This has been working very well for me as I am somewhat OCD when it comes to keeping my machine/workspace organized.

I'd love to expand on Jeremiah's idea a little.

I imagine you have a nice music collection, and you may have thousands of songs, from hundreds of albums, from dozens of bands, but there's a clear and easy way to organize them.

Instead of trying to sort your music by style or tempo or key signature, sort them by who makes them, much like iTunes does.

Think of your fonts as songs, your font families as albums and the foundry as the artist. I think it's a really simple idea and I find it works well!

Just as in iTunes, instead of letting single entries clutter it up, I have a catch-all generic artist that I put all of the loose ends in.

Also, if you're on a mac and don't already have professional font-management software, there's a free tool (sorry mac-only at the moment, windows port is in the works) offered by Linotype called FontExplorer X. It has an interface similar to iTunes and I've found it very useful.

Another cool feature of this, is that it allows you to enable or disable selections of fonts, so you could easily create a 'playlist' of all the fonts used for specific projects and also manage them that way too!

Some earlier threads can be found here.

And I will expand on innovati's iTunes comparison and suggest "playlists". Unlike most of the typophiles here I don't organize by foundry (except rare exceptions like Emigre and House Industries) because that's not how I think of fonts. I don't sit down and say... hmm for this project I'd like to use something by Matthew Carter. So I have sets based more on the attributes than who designed or sold the font. My sets are
antique/distressed
calligraphic/uncial
check these out (new fonts I want to use)
condensed
deco
dingbats
display/ornate
emigre
expert collections (for text fonts)
funny/silly
groovy
grunge
handwriting
house
nouveau
open type
retro
sans
script
serif-display
serif-text
slab
techno/futuristic

I keep my fonts organized by foundry in alphabetic order. Someday I'd like to add tags using descriptions, as Patty has done, and use smart folders too. But for not foundry helps me out the most because in my head it also separates them by EULA and quality. :^)

I use the foundry method. Plus I have separate folders for decorative/novelty and borders/dingbats since I use these less often. Another category I keep separate is pixel fonts.

But, for me, the most important category of folder I use are my project folders. I make one for each project so I can easily activate the fonts I need when I am working.

Sharon

Sharon - I used to make sets for each project but FontExplorer (when it's working properly which mine is not right now) activates the fonts for you. I still sometimes make a set right at the beginning when I'm still testing out the fonts.

Organizing by Foundry would be useless for me. It's so not the way I approach design. The old Font Reserve had foundry info as part of the interface, I'm surprised FontExplorer doesn't do that. It doesn't seem to let you add or customize it either.

By foundries in the libraries. I say libraries because I keep a master library on my Data drive and a smaller library (duped from the master) on my System drive that is where I import into FontExplorer from. The reason for that is the most common thing that corrupts fonts is when a program crashes while the font is activated.

By having two libraries I never activate the master font (and I don't like FontExplorer to built it's own little library). Freak, I know…

In FontExplorer I organize by style.

pbc

All ideas, theories and statements are subject to change without notice.

The old Font Reserve had foundry info as part of the interface, I’m surprised FontExplorer doesn’t do that. It doesn’t seem to let you add or customize it either.

Patty, you can do this in FEX, too – although it is a little bit hidden:
You can both customize the ‘Information’ panel (ctrl-click on the panel, or via View > Show Information > Customize) and the column view (ctrl-click on the tabs).

I hope they get Font Explorer for Windows working some day. That would be nice. :-)