[jtheory]

Meh. Look at the example reasons in the post you're responding to; you don't need an answer like "I want to save the world, and I'm pretty sure the best place to start is in the plastic chair manufacturing sector".

If the best you can offer is "uh I need a job" that means you don't know a damned thing about the company you're applying to, doesn't it? I.e., you found a list of 30 companies that are offering jobs in your city that vaguely match your CV, and instead of reading about them and choosing a few, you're taking the shotgun approach.

If you read about them, what made you choose this one?

Do they seem like they have a culture that's better than your last job? Do they use a language you like (and/or would like to use more)? Are they doing something you know anything about, or find interesting at all, or can at least categorize as "not morally objectionable"? Almost anything is better than "I need a job".