Update (2020-08-07): This is a republish of my fifth blog post, dated 2010-06-21: Interview Pet Peeve. Devblog won't let me backdate this before 2015.
This is a plea to any and all companies that are interviewing Software Engineers: require that your job candidates write code. This, in and of itself, isn't new. If you've read The Joel Test, for example, you'll find this as requirement #11. But I want to add to that: ABSOLUTELY NO WHITEBOARD CODING!
When was the last time, other than in an interview, that you pulled out a dry-erase marker and wrote fully-functionally, syntactically-correct code on a whiteboard? If you can name a time you've done that (and it was more than a few lines), then you're doing something wrong.
Computers are cheap now. Buy one for your conference room, or wherever else you carry out your interviews. If you don't want to install actual development tools on the computer for some reason, at least let your interviewee code in Microsoft Notepad. You can even let them use some netbook computer if you have to. Or, let them use a smartphone to type it in! Heck, you'd be better off offering him/her an old-style typewriter rather than a whiteboard -- they can't edit and insert with either input device, but at least with a typewriter they can have the benefit of entering code fast.