For those among us for whom the standard OS dock is too conventional, too simple, too small, too narrow, too … … (you name it):
an application with multiple docks in the form of libraries: flexible, very customizable, easy to use. In my opinion, worth its money.
If you’re interested in a similar application: Try, and see for yourself.
One that I’ve used since the dark ages of Mac Classic is DragThing. The amazing thing is that I’ve had a licence for this for over a decade now, and I’ve only paid for one upgrade. It is consistently maintained, and likely the most powerful tool of its kind. It’s been doing “the Dock” since before Apple bought the notion from NeXT.
It’s a bit of a power tool though. The breadth of its options can be overwhelming. Each “dock” has its own barrage of settings, and within each dock you can have tabs which also can have their own settings. It takes some time to get it set up to the way you work, but doing so is rewarding. My favourite aspect of it as that you can create very “thin” docks. Translucent, small, and out of the way until you need them. You can create big fat ones too, if you want, though.
The only reason I stopped using it was QuickSilver and LaunchBar. They totally changed the way I interface with a Mac.
Yes, Launchbar is indeed an excellent application. I love it, and I use it daily.
But Berokyo offers, like DragThing, I suppose, the possibility to sort the most frequently used documents and applications by type. I have one Berokyo library with the articles I’m presently working on, another with diaries and other private documents, a third with all my Scrivener projects, a fourth with all Desktop documents, and so on, and they all can all be opened in a split second. I find this very convenient.
That is true, where these extended docks have an advantage is where you have frequently accessed material that is otherwise clunky to get at with LB or QuickSilver. If you have to descend into four folders to get at something with LB, every single time, then having a single click solution right on the side of the screen is good stuff.
Ioa, do you used both QS and LB? Never having heard of them, I took a peek at them and saw a lot of overlap between the two. If you do use them at the same time, what makes LaunchBar worth the extra money over the free QuickSilver?
No, that would be quite a strange thing to do, as you note they are practically the same thing. I came across QuickSilver first and used that for a few years, but then for a while it was not being maintained very well and had a lot of bugs, so I decided to give LaunchBar a try. So at this point I couldn’t honestly give you an opinion between the two, as it has been at least four or five years since I’ve used QS and I have no idea what state it is in at the moment. LB is rock solid, powerful, and despite being a keyboard tool, very “Mac-like” and easy to extend if you know a scripting language or two, but especially AppleScript. Whether or not that as worth the extra money at this point in time, I don’t know—but there was a time when it was.
I think Launchbar is excellent, as Ioa says, frugal on resources, great for writers where you want to do everything from the keyboard and more solid than Quicksilver for the last few years.
However, worthy of consideration if your needs are relatively simple, and coming up on the rails though still some way behind in functionality is Alfred with its Powerpack. Alfred looks better than Launchbar IMO and is being developed very quickly, but unlike Launchbar it can’t launch Applescripts (for example) and it can’t climb back up a folder tree. But maybe it will soon.
Rock solid? I took Don McAllister’s advice (in a pair of ScreenCasts Online videos a year or so ago) and added all of my files to LaunchBar’s database. Bad idea. Crashed five or six times a day. However, now that I’ve pruned the set of files, it is rock solid. Just don’t grossly overload it.
Just another hand raised for DragThing.
I procrastinated for about two years before moving from Tiger to Leopard, mostly because of DropDrawers, a similar app that was born in the era of OS 9, or 8 or even 7? I don’t remember. But I grew dependent on those slide out drawers and when development ended after 10.4, I just stayed with it.
Then I got a cross grade for DragThing and finally my transition to 10.5 was smooth. 
DragThing is a fantastic help, bluntly put, and the dev, James Thomson, is super alert with support. Not that I needed any support per se (IME, DT is totally stable) but as Ioa remarked, there’s a lot of options that can be bewildering. In essence James just helped me RTFM.
Wholeheartedly recommended!
/Joachim
It’s great to see DragThing, Drop Drawers, and LaunchBar mentioned. I’ve used them for a very long time.
These days I only use LaunchBar out of those. I could never get into QuickSilver and had been using LaunchBar probably since version 1. I got it in a bundle named Ten For X, by Aladdin (later Allume, Smith Micro).
My Dock replacement has been WorkStrip, from 2002(?)
softchaos.com/products/ws3/ove.html
softchaos.com/products/ws3/pro_tou.html
In a way it reminded me of the old Control Strip modules when I got it, but it’s really more like a VERY powerful Dock. I never liked the Dock, btw.
It has something called Workspaces. I have one called Office with all of my Office applications. Another one called Audio with my audio recording/editing applications.
It has a history for recent applications, recent items (by date, by type), and when choosing a recent application it has another sub-menu showing recent items specific to that application.
I can hover over the recent application Word and see the most recent item (a Word file) or hover over a specific date and see a list the items I opened on that day, and if I hover over a specific item I can even get a preview of the contents.
I’m happy that it still works on my PPC Mac running 10.5.8, but the latest release is from 2006. I don’t think they even had an Intel-specific release.
SoftChaos went out of business, but WorkStrip has got to be one of the finest applications I’ve used.