How do you keep your business organized? Do you keep everything (contracts projects, sign offs, comps), all on your hard drive? Or do you also have old fashion paper you use? Do you keep each client in their own folder or do you use note books or both? How about storing away your projects once they are completed? In short, how do you stay organized with multiple projects with multiple clients at one time?
Everything I do is digitized, stuff like bank statements, related mail or business documents on paper are scanned into the computer into PDF format and everything is organized into appropriate folders, archived stuff (I no longer need) is compressed into a RAR archive and all of the content is synced between my secured web storage account (off-site) and a couple of external thumb-drives (one which I carry with me everywhere), the other is in a safe place. 
I keep each client in a separate folder on my harddrive and they each have a physical notebook and folder for different documents and notes I take.
When I meet with a client I rarely take a laptop so the notebook is for all of their desired functionality and any notes I have on them. The harddrive is simply for the deliverables and the different documents I need to send to them or ones I receive from them.
I keep a folder in my “Clients” section with a subfolder for each of communications, contracts, etc. and a subfolder for the site itself. For customers who have come back for site “refresh” after a few years, I have subfolders that are named “_site-2010”. Of course, everything is backed up.
I also keep a physical folder for each with signed contracts and just my rambling notes. I take notes often when I’m out and about and get a moment and an idea.
I never consider a client to be “completed”, there is always an opportunity to sell services for maintenance, updates, SEO. But I keep active sites I am designing in a folder tote on my desk and sites that are in maintenance mode in my file drawers since I’ll be getting into them less often.