I keep an Excel file open at work.
In it I list all the projects I am working on.
I then highlight the cells to color code them.
White are daily projects that have to be done right away.
Yellow are projects I have finished a draft of and are waiting for people to get back to me with changes and such.
Purple are long term projects (updating the website, etc.)
Blue are projects people have told me they want me to do but have yet to send me all the things I need to start them.

For the first time in like 6 months I have nothing in the white. I usually have about 15 things in the white. I still have 22 things in my agenda, but I can't work on any of them right now. Man, this feels good.