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If you’re writing code, there is a video of a good talk by Joshua Bloch on designing good APIs. It has a Java slant, since Joshua is one of designers of Java APIs, but the advice is generic enough to apply to other languages. Beware the video: it’s in flash but uses a bad player that cannot be paused (well, it can, I just couldn’t unpause it) so be prepared to sit through all 70 minutes of it at once. To all video providers: please also provide a version that I can download and watch in my favorite player at my leisure.