is there software you can put on a flash drive, then plug that drive into a computer and then have access to that computer from a second, remote computer? I would love it if someone knew a way how. Thanks for your time!
Cross-platform remote access applications such as Teamviewer could be loaded on a USB flash drive and run directly from the flash drive. You will need the binaries loaded on the flash drive for each operating system (i.e. Windows, Mac OS X, Linux).
Teamviewer can be download from http://www.teamviewer.com and is free for non-commercial use. Additionally, it allows access through most firewalls as long as surfing the internet is possible on the remote computer (Source: http://www.teamviewer.com/en/help/334-Which-ports-are-used-by-TeamViewer.aspx).
An alternate solution would be booting to a pre-configured Linux installation and using a reverse SSH tunnel to provide remote access to the system. Bootable Linux flash drive can be created using your favorite Linux distribution's ISO and the pendrivelinux utility http://www.pendrivelinux.com/