Email etiquette: Thanks

I grew up being taught to say please and thank you as just a matter of simple courtesy for actions large and small.  But more and more, I find this to be at odds w/ polite and efficient email practices.  A quick scan finds a number of other people with similar opinions:

Is your e-mail necessary, important or useful? If not, don’t send it. That includes unnecessary replies, such as “Okay, thanks,” or “Take it easy.”  - TheWritersBag.com

My personal view is that just saying thanks as a way of acknowledging an email is pretty pointless. But expressing gratitude in the right context is a necessary part of courtesy. -  badlanguage.net

Don't send e-mails that simply say "Thanks." - fabjob.com

and some strong opinions on both sides of the issue in response to Paul McNamara's blog entry on the question Thanks or no thanks?

Now, there are many lengthy projects/exchanges or situations where people put in a lot of effort, and those cases merit an actual response expressing your gratitude.

But if the appropriate level of response to someone's email is simply "Thanks" and nothing more, then I lean towards just not sending anything - and expressing your thanks by not popping up one more thing on their Blackberry or one more item in their inbox for them to delete.

So, if you've forwarded me an interesting article recently or answered some question with a quick helpful one-liner response and didn't hear back - Thanks!