The book The Pragmatic Programmer is absolutely worth re-reading every few years, because every page has stuff on it that's still relevant. One of the important lessons is "Keep knowledge in plain text". To paraphrase, you shouldn't keep important information in a proprietary piece of software, because if the software dies (because the company goes out of business) or it relies on a changing protocol (more about this in a second), your knowledge is trapped. If you keep it in plain text, you can read (and manipulate it) using a lowly text editor.
Two things made me realize this in a Big Way recently. The first was my ToDo list. I used to keep all my ToDos in a good (but fatally proprietary) piece of software named LifeBalance. It's the best of that category of software, but using it meant that I had to have a Mac OS X, Windows, and Palm client to access it. It became its own project just to keep it in sync. And, unless LifeBalance works instantaneously, adding items takes time. I was reading the LifeHacker book (distillation of the awesome LifeHacker web site) earlier this year, and one of the first items is an entry about a text-based ToDo list manager called ToDo.txt (which has its own website). It's called "Task tracking for command line lovers". The nice thing about ToDo.txt is that it uses a plain text file for storage. And, the author has written a bunch of bash/batch files to help manage it. That means you can append stuff of your own (using QuickSilver, in my case) or you can use the tools. The command line tools also let you prioritize, archive, and a bunch of other stuff. It's a good marriage between command line and plain text.
The other driving home of the important "Keep knowledge in plain text" lesson concerns my blog. For years, I just wrote my blog entries in a text editor in HTML and uploaded them by hand to Blogger. Last year, I fell for a seductive blog editor/manager called MarsEdit. It works fine, allowing you to create drafts, view your blog, handle multiple blogs, etc. The way it did this was via using one of Blogger's APIs for managing blogs.
Then something terrible happened: Blogger changed their API. Suddenly, MarsEdit didn't work anymore. Posting new entries wasn't a problem because I could go back to doing it by hand, but what amount my 9 months of existing, historical blog entries it held? Trapped! Now, I can't use it, and I can't easily free all my information. I violated the rule!
I just spent a couple of hours fixing this mess, re-syncing my original directory structure by hand (at least I was able to use wget to slurp my whole blog down to my local machine, making it much easier). I've felt the pain of violating the rule, and I promise not to do it again. My last step was removing MarsEdit from my machine (which, BTW, has now updated itself to work with the new API -- unlike our president, I remember the phrase "Fooled me once, shame on you, fooled me twice, shame on me").
Of course, Dave and Andy already knew this, and they told me, but I wasn't listening. Sometimes, you have to suffer for good advice to take hold.