Like everyone else, when I started dabbling in AJAX code I found myself repeatedly creating the same code to do the same things. There was always code to make sure I could create the XMLHttpRequest if it was there, or the Microsoft equivalent for the awkward browser. There was always event code to process, sometimes repeatedly, the response codes until I got a 4. There was usually code to present some visual indication to the user that there was a call in progress.
Now, like other programmers, if I find myself doing the same thing over and over again, it's time to write a library.
I'm not convinced that this is relevant any more, but I find it handy to see the web safe colours all together like this when making sites. The web safe palette also limits your options which makes it a little easier to make a decision about which particular green you're looking for.