Adobe Acrobat Reader 7.0 is a quantum leap over the slow, twitchy, takes-forever-to-do-anything 6.0. It loads so quickly that you can open a PDF in a browser window, and it doesn't take substantially longer to come on-screen than an HTML page would. This is a vast improvement. I now routineley just open PDFs online, whereas once I would insist on downloading them first, and swearing a blue streak if I accidentally just clicked a link to one. It also interfaces with Firefox much more smoothly.
AVG Anti-Virus 7.0 is also a great improvement over the previous version. Before, if it caught a particularly virus coming into my mailbox, I'd have to shut down Pegasus Mail and do a custom scan on the mail directory, then clear out the Virus Vault. Now, it's transparent. After installing it, I noted that I hadn't had any "hits" in a while. I opened up the control panel, and the Virus Vault had ten of the little bastards sitting there under lock and key. All I had to do was hit a button to flush'em. No interruptions in my mail, or anything.
So... as Apple reserves the right to remove functionality from your iTunes at any time, and as Windows Media Player gets crappier and crappier with every iteration, it's nice to know that there are some software companies that, now and then, actually understand the meaning of the word "upgrade".