Growl, is a utility for geeks only. It basically unifies all the notifications from most of your Mac software and gives you total control of how every background action or event is brought to your attention: Pop-overs, sounds, events, email or even remote computers can receive alerts on the style that you stipulate. A must for any technically-oriented Mac user. (To be honest, it should be integral part of Mac OS).

Stuffit Expander, by Smith Micro. This is the grandad of the archiving utilities for the Mac. Although the OS can archive and decompress in Zip, Stuffit will open vitually any other format out there. I suggest you install it, and in preferences, assign all types to be opened by it, then activate to delete the source archive after decompressing, and set to watch the Downloads folder to open archives automatically.

Awaken, by Embraceware Software. A multi-purpose alarm clock and timer. Programable to do almost anything you wish on your computer at a determined time. A lesser alternative is Aurora, by Metaquark.

Flip4Mac, by Microsoft. This component will allow Quicktime to play the popular WMA and WMV video formats. You need this as much as Perian!

Perian, is a package of codecs for Quicktime that will allow it to play any video format that may not play already natively (AVI, DIVX, MS-MPEG4, etc, etc). You need this (non-optional, really). For additional support of WMA, get Flip4Mac.

Coda, by Panic, is a friendly, inexpensive alternative to Dreamweaver. Probably not what you would use to develop a full-fledge web service, but pretty handy to tweak a static microsite

Connect360, by Nullriver. If you have a Xbox 360, and you want to stream your media (photos, video, music) from your Mac. This is it.

MediaLink, by Nullriver. If you have a Playstation 3, and you want to stream your media (photos, video, music) from your Mac. This is it.