Dibs work fine for me, although once I offered one of my cels to an interested 
buyer and never heard back but I wasn't in dire need of money at the time.  Thank goodness.

and....
If you have a bad memeory all you have to do is keep a word document, i use
a simple text document (mac person), to keep track.
Whenever someone is interested in any of my cels I just open up that file and 
add their e-mail and what cel they are interested in.  It's pretty simple me thinks.
I'm not one of those really organized people but I find it pretty easy to keep a 
list right in my cels folder.

Ja ne,

Kelly  ^_^