Windows only: iSwitchw filters through a list of open windows as you type—with a semi-transparent dialog accessible by simply pressing the Caps Lock key.
To install the script, you'll need to create a new *.ahk file and paste in the contents of the script found in the link below. Once installed, using iSwitchw is easy enough—just launch the AutoHotkey script, hit the Caps Lock key, and then start typing to filter down the list of open windows, or use the arrow keys to select from the list.
Once you've found the window you want, simply press the enter key to switch to that window—it works very similarly to the find-as-you-type feature found in the Switcher 2 Mac Exposé clone, but instead of showing a visual preview like Switcher does, there's just a list of window titles—once you get used to it, you'll wonder how you worked without it.
iSwitchw is a free download, requires Windows with AutoHotkey—and since it's implemented as a script, you can easily modify anything that you don't like, including changing the hotkey to something else—so if you are using your Caps Lock key for hand-friendly navigation, you can still use this script by assigning a different launch key. If all this AutoHotkey scripting goodness is new to you, learn how to turn any action into a keyboard shortcut.
iSwitchw - cosmetically enhanced edition [AutoHotkey Forums]