/data/data nightmare: FC's because of 100% Utilisation I feel like I need to clear things from /data/data every 2 to 3 days to prevent cascading FCs when it becomes 100% full. Is there any possible way to move any of that data to the SD card (and still have it be accessible from my apps), or to increase the maximum size of the folder? I am rooted and running cyanogenmod 7.1 on my HTC Incredible. Thank you all so much for your assistance.
Have you tried moving your Apps to the SD Card?  Go to Menu -&gt; Settings -&gt; Applications -&gt; Manage applications -&gt; Downloaded tab then tap on any 3rd-party app and then tap on the Move to SD card button (if available.)  This should move most of the app to the card, thus freeing up space on the /data/ partition.  Not all apps support this method, but do try it on the largest space hogs like Flash Player and Adobe Air, for example.

Unfortunately moving Apps to SD Card this way doesn't touch the apps' cache or Dalvik cache.  To move those you'd need the old-school "apps2sd" hack.  The basic idea is to re-partition your SD Card and create a 2nd partition with Ext2/3/4 format.  The contents of /data/ folders are moved to the SD Card's Ext partition and the phone's internal memory is therefore freed up.  Then a script is added to Android which mounts this partition at boot time and links /data/app, /data/app-private, /data/data, and /data/dalvik-cache folders to their corresponding locations on the SD Card's Ext partition.

There are some apps on the Market that automate this (except re-partitioning the card, which you'll need to do manually.)  Try Link2sd or Simple2ext for example.  Of course make sure you have a nandroid backup of your phone before trying anything.

There are obvious pros and cons to this method. The pros are the ability to greatly extend the phone's storage for apps, while keeping the internal memory relatively free.  The cons are inability to cleanly un-mount and remove the SD Card (since the apps are mounted on the 2nd partition that the OS isn't aware of,) and possible slow-downs in launching apps depending on the speed of the card.  There SD Card will also be subjected to more wear and tear, since it will be used by the system for reading/writing more than usual.