Like most of us, I've come to rely on Apple's Software Update to tell me when new updates are available. It seems that most third-party software has its own built-in mechanism for checking for updates as well, so I hardly ever go to http://www.VersionTracker.com or http://www.MacUpdate.com to look for new releases any more.
I've discovered in the past few weeks, though, that I've missed some updates, because the built-in updaters haven't alerted me that new software was available.
One of these packages is the Adobe Acrobat Reader, now just called "Reader." I know that it has its own updater, but version 9 never told me that version 10 was available! I had updated Reader up to 9.41, but it doesn't offer to upgrade to Reader 10, which came out back in October! I had seen an article on the web that mentioned that Reader X wasn't susceptible to the latest malware attack. I didn't remember getting Reader X, so I opened Reader, and checked the version number in the About box -- 9.41. I manually ran "Check for Updates" and the Updater ran, and told me that I had the latest version. I went to Adobe's website (http://get.adobe.com/reader/), though, and found that 10.0 was available. I had to manually download and install version 10 last week, but its told me today that version 10.0.1 is available (and its updating right now!).
Another one of the other updates that I hadn't gotten was for the "Flip for Mac WMV" plug-in that allows playing Windows-format video clips on websites. It also has its own "Check for Updates Automatically" preference, but hadn't updated to the latest release that came out months ago. I had to open its Preference Pane, and click "Check for Update" myself in order to get it up-to-date.
I was also changing some settings in my Qwest DSL router last week, a Motorola Netopia, and clicked on the software update tab. It said that there were no updates available. The next day, after getting an ad suggesting that I upgrade my DSL to fiber optic, I went to Qwest's website to see if faster speeds were available in my area -- they aren't... But while I was there, I went to the Modems page (http://www.qwest.com/internethelp/downloads-auto-firmware.html), and clicked on the link for my modem, and found that there was a update almost a year ago that I didn't have yet. I had to manually download the firmware image, and upload it to the router through its web interface, and now it actually seems faster! There might be firmware updates for your wireless access points and routers, as well as your DSL routers or cable modems. It doesn't hurt to check...
While we normally think of software updates as adding new features, and perhaps fixing some bugs, many updates also address security issues, fixing vulnerabilities in the software or devices that might allow hackers and viruses to get through, so its always a good idea to keep your software current. Even if you have turn on auto-update everywhere, and have Check for Updates run automatically, it doesn't guarantee that everything is going to be up-to-date. Take the time once in a while to manually check for updates that you might not have gotten.
Another suggestion, if you have the latest version of Snow Leopard (10.6.6) is to check out the "App Store" application. I've re-installed several apps that I already had installed, using the App Store, as it has an Updates tab much like iTunes, that will also check for updates for your installed applications.