PlugINCool is a simple and easy to use plugin manager for Mac OS X. Thanks to this software, you can easily add and remove plugins for: Dashboard, Screen savers, Spotlight.

LeopardMOD is a Mac application that will allow you to easily modify Leopard’s hidden settings, making use of a simple interface (without having to use the command line).

Textmate is a popular and powerful text editor (not free) for which you can download a variety of plugins. Blogmate (free) is among the most functional of these plugins, allowing you to write and edit blog posts from within Textmate. It’s tested to work with WordPress blogs, but should work with any blog that allows XML-RPC publishing. If composing blog posts in a text box isn’t cutting it for you, try Blogmate.

David Allen wrote the book on Getting Things Done, which has some great principles for increased productivity. For a summary see the Wikipedia article or Merlin Mann’s 43 Folders.

iGTD brings David Allen’s workflow to the Mac, including an inbox, projects, contexts, pending, “maybe” taxes, and “waiting for” tasks. You can drag tasks between contexts and projects, and you can drag Address Book entries into iGTD.

It also comes with a Quicksilver plugin so you can funnel stuff through Quicksilver to the iGTD inbox.

I wish I could list tasks in multiple contexts and simultaneously in projects, but overall iGTD facilitates the GTD workflow pretty darn well.

Many of my friends have Facebook accounts, so it’s a great place to stay up to date on what they’re doing and to see their photos. While it has a pretty good interface for uploading pictures, this plugin make it’s even easier. With the Facebook Exporter for iPhoto, you can send photos directly from iPhoto to Facebook. You can also put them in albums, add captions, and tag them. If you use Facebook and iPhoto, you’ll definitely want this plugin.

TabStop does just one thing. It warns you if you are going to close a Safari window that has more than one tab open. No more accidentally quitting a browser that has a hundred great articles open and ready to read.

If you have tabbed browsing enable in Safari, you will appreciate this app.

If you have a USB camera that isn’t supported by Mac OS X, you’ll find this freeware very useful. “Macam is a driver for USB webcams on Mac OS X. It allows hundreds of USB webcams to be used by many Mac OS X video-aware applications. The aim is to support as many webcams as possible.” And it does support a ton of cameras.

I should note though that this program isn’t setup to have your camera be compatible with iChat. But for other things like iMovie and Quicktime, this should work well.

If you’re into music and enjoy a good concert, this is the plugin for you.

iConcertCal is a free iTunes plug-in that monitors your music library and generates a personalized calendar of upcoming concerts in your city.

I just fired it up for my hometown of Las Vegas and sure enough, there are all kinds of folks playing here

If you browse the Internet with Camino and open lots of tabs, you run the risk of losing all your work if you accidentally close the browser. CaminoSession protects you from this by remembering which tabs were open and re-opening them for you. (Forget Me Not does the same thing for Safari.)

Forget Me Not is a Safari plugin that helps you reload tabs or windows that were accidentally closed.

There’s nothing worse than opening up a bunch of articles to read and then pressing “Command-Q” instead of “Command-W.” Just like that, Safari quits and there fos all of your reading opportunities. Forget Me Not will make it so when you open Safari back up, all the tabs will come back as well.

It also works when you accidentally close a tab or window as well. Just hit “Command-Z” and it pops back open.

(PS, This is only really helpful if you decide to enable tabbed browsing in Safari…which you really, really should do.)