If you run TM you don't really need local snapshots so if you need the disk space you can disable them in Terminal by copying & p;asting this command at the prompt
sudo tmutil disablelocal
Press return. You will be prompted for your password, it will be invisible.
To undo this, rerun it with "enablelocal" instead of "disablelocal".
In TM preferences you can choose to exclude items to the backup.
EDIT: See these helpful hints from Pondini.
What kind of things would I exclude though? I mean 640GB is alot to back up only 77GB of Data
You would exclude any additional partitions you may have on your Macbook Pro and any external drives like USB drives that are attached via the USB ports or Firewire or Thunderbolt ports.
For example, I have Macintosh HD, Lion HD and Test HD partitions on my rMBP. I exclude the Lion HD and Test HD in Time Machine so only the Macintosh HD gets backed up.