Session Scalablity

[eluser]codelearn[/eluser]
Hi guys-

I'm having a slight problem with sessions. The new version of my website allows people to drag and drop widgets around (like http://www.campuslive.com/umass). This means that every time they drag and drop, it saves it in the session. This is causing my tmp folder to BLOW up to 1 gigabyte every couple days.

Is there a way to overwrite sessions? I'm just using session_start().

Any help would be amazing, thank you.