If you are like me you have to have a Yahoo! IM account, an AIM account, an MSN account, etc. Trillian allows you to access all of these from the same program and the same window, simplifying your instant messaging life.
If you go on a lot of business trips, Skype is an absolute must. Video chat is completely free, so both you and your significant other can get face time even when you are halfway around the world. If you insist on doing it the old fashion way, you can call a telephone anywhere in the world from your pc for lower than normal rates. Also has regular text chat.
VLC can play almost any type of video or audio file you can think of. Since I got VLC, I haven't opened QuickTime or Windows Media Player, and there hasn't been a file that I was unable to view or even had trouble watching. VLC is a must, especially if you download torrents.
Speaking of torrents, Vuze is the greatest client I've found for that. Search multiple sites from inside Vuze, it has an easy to use download manager, and even has videos that are exclusive to Vuze users. It's the new and improved Azureus. The best part is probably the torrent reviews you see in the searches.
CDBurnerXP allows you to burn CDs, Blu-Ray and HD DVDs, and create ISO files. Awesome interface, easy to use, I haven't had any problems with it so far.
I currently have four email addresses that I need to check regularly - work, school, Gmail, and AOL. Thunderbird allows me to check all of them in one window, check for updates to all of them simultaneously, and also has a calendar and task list. Thunderbird is made by the same people (Mozilla) that make the Firefox browser.
Even though most people know about it and already have formed their opinion, I might as well mention it. Firefox for me has been worlds better than Internet Explorer, and also even better than Opera. It's secure, the add-ons allow me to add whatever functionality I want to it… if you haven't tried it, you need to.
