There are quite a few apps on my machine that run in the background, waiting for that moment when they get to shine. These apps augment the OS X experience in ways that I’d have trouble functioning without.

This is a list of my top picks at the moment. Though the list changes frequently, most of these have been long-standing choices on my machine and have survived several re-installs and cleanings…

You’ve heard me talk plenty about TextExpander. It’s easily the most-used application on my computer, assisting with just about every task that involves typing.
BetterTouchTool is another app that is in such constant use that I get confused using machines without it. It not only adds vital functionality to my Magic Trackpad, it also maps a lot of keys on my keyboard for launching applications and triggering scripts.
I’ve spent a lot of time tweaking PopClip, and it’s to a point where I use it as often as I use Services with shortcut keys. I essentially use it for running scripts that would normally be Services, but are now easily accessible when I’m making mouse selections.
TotalFinder is kind of a background app, but definitely an augmentation. It adds split panes and tabs to Finder, along with some basic tweaks like Command-X cut and paste of files. Much of its functionality won’t be necessary with the advent of Mavericks, but for right now it’s a must-have for me.
Default Folder X
Default Folder X augments Open and Save dialogs, adding recently-used folders, default folders for different apps, quick access to favorite folders and – importantly for me – OpenMeta tagging (which I assume/hope will update for Finder tags in Mavericks).
With all these background apps running, Bartender keeps my menu bar sane. It lets me allow any of these apps to show their menu bar icon for easy access to settings without actually having them appear in the main menu bar. Without it, my menu bar would make me crazy, especially on my 13” Air with limited screen space.
Moom gives me keyboard control over my windows. It lets me use hotkeys to center and maximize windows, expand and shrink, snap to edges and more. It also lets me create “snapshots” of app combinations to automatically position windows based on running apps.
If you run a few (or more) AppleScripts regularly, FastScripts gives you a quick menu and customizable keyboard shortcuts for triggering any script. Like the regular Scripts menu, it can sort by foreground application and keep your menu trimmed down based on what’s currently available.
Hazel watches my folders for changes, and runs various scripts to help organize my files quickly and without interaction. Notably, I have a script that watches for files on my Desktop to receive OpenMeta tags, then files them into my folder hierarchy based on “target” folders I’ve previously tagged. It can do much more, and has a flexible “rules” dialog to easily build complex parameters.
This one is slightly less essential, but once you run it for a week you’ll miss it when it’s gone. It changes your screen gamma after sunset to give you an easier-on-the-eyes display for late night hacking.
PCKeyBoardHack and KeyRemap4Macbook
I’ve come to depend on my Hyper key, and it depends on these two utilities to function. KeyRemap4Macbook also provides a wealth of other keyboard remapping tools. I especially like the Vim mode, where I can hit the Command key on the right side of my Space Bar one time and have Vim navigation in any Cocoa text field (and for navigating menus).

I’ll admit that I typically have more than this running. I’d be almost embarrassed to detail all of the things that are eating my CPU cycles. Almost1. These are the top ones I recommend checking out, though, if you want to push OS X a little further.

  1. I have a shortcoming in the shame area.