The Overflowing In-Box

I'm not talking about my email in-box, I'm talking about the real, 3-D in-box sitting above my desk in my home office.

New stuff that comes in -- magazines, important mail, etc. etc. -- goes there. But if it isn't super urgent, it STAYS there. And stays. And stays. 

Here's why: I have lots of defined tasks most days, and I tend to fear that my in-box will become a time sink of off-topic tasks that take me away from my defined tasks. Very few of my defined tasks are anchored to anything in the in-box. 

For that matter, the same problem appiles to my email in-box. While I read e-mail throughout the day and can often act quickly and ditch something (a good thing), anything that's not urgent piles up there with no clear definition of what to do or how to do it. 

I'm going to look over my two David Allen books -- Getting Things Done and Ready for Anything -- for reminders on what to do about this situation. But in the meantime, if anyone here has had a similar relationship with their in-box or -basket, and especially if you've figured out how to combat it -- I'd love to know.