Several of my gmail labels have a corresponding labelname-to-reply label.

I realized I was using my inbox for several functions:

1. notice urgent or topical subject lines

2. store items to read later

3. store items to reply-to later

4. store important already-read items for later reference

5. store to-do items, often implicitly as 2-4 above.

Once I set up the appropriate labels, I was able to move functions 2-5 out of the inbox, leaving it just for function 1.