SoBig is a Control Strip Module that shows the available RAM and startup disk space. The upper number with the memory chip icon is the amount of RAM available for new applications. The lower number with the hard disk icon is the amount of disk space available on the startup drive. Click on the module to see a menu of available space on all mounted drives. When used with Apple's Control Strip, SoBig is sensitive to whether the hard disk is spinning or not and will not update the available disk space unless the drive is spinning. The drive will spin up when the list of all mounted volumes is displayed. Desktop Strip always reports that the drive is spinning, so SoBig always updates the numbers.
Of course, you need Apple's Control Strip or Desktop Strip by Men and Mice to use SoBig. SoBig 1.1 is free but not public domain. You may distribute SoBig 1.1 so long as you include this README file and do not modify either file in any way.