Where can I find a `datasheet' document class or a tutorial on how to create one?

How about the papertex class? This is designed for a making a newspaper, but that only allows you to do more than what you want. After a quick scan of one of the data-sheets you linked, it seems that it would be rather painless to subvert papertex to your liking.

Hope it works for you!

I didn't find one either, so I made a simple document class imitating the common style of electronics datasheets.