Dark have been my days of long. For years, I've been trying to abandon the Dock so that I can save some very precious screen estate especially because most of my life I've used (and am still using) screens that are approximately 1024 by 768 pixels. Every pixel on my screen is precious and with Overflow, I get 71680 pixels (or about 9% of my screen) back from the clutches of the Dock.
It's basically a very nice launcher. I usually launch a lot of things using Spotlight, which is all well and good except for the fact that it takes a couple of seconds. Overflow is basically a window that pops up when you press a certain keyboard shortcut and displays an array of icons that you can click to launch. Very importantly, you can also type the first few letters of an item to directly go to it. This means that if I give it a keyboard shortcut like Option-Space (by default, it's F1) and enter the first few letters of the name, I'm basically launching the thing in exactly the same way as I would have with Spotlight except for the fact that it's instantaneous.
Some might argue that QuickSilver is what I need, but I would have to disagree. QuickSilver is very powerful (and very free) but it's overkill for my needs. The list of applications I want to launch is very limited and QuickSilver has a much larger footprint than Overflow. However, when I'm searching I usually want the pervasive power of Spotlight and when I'm launching I need the small footprint and even more instantaneity of Overflow. QuickSilver is something in between, but is the perfect balance for a lot of people.
The only downside of Overflow is that it's $15 instead of free or donation-ware which is a more apt price for such a simple app. However, this tiny app (1.2MB as UB) is quite indispensable for my workflow (after only 24 hours of using it) and I definitely recommend a try. It's like NewsFire for RSS, there's nothing better, sleeker and simpler.