As a developer, good ways to store those often-reused snippets of code that correctly solve a common problem is always useful. Now, there are other solutions to this problem, such as the Snipt API, which I covered previously, but Pastebin.com is the most often used, perhaps because it has beeb the favored place for notes from hacker group LulzSec. Pastebin has a nice, full-featured API, and is simple and free to use, at least at a basic level.
There are a number of ways to discuss API popularity. Our metrics are based on developer engagement. The "track" functionality on ProgrammableWeb lets developers declare an interest in receiving updates on particular APIs. Which APIs and categories are seeing the most activity.