LibreOffice.Org
has a free (and excellent) office suite of software. It even reads .docx and .xlsx files created by Microsoft Office 2007 & Office 2010.
PortableApps.com
has many programs which can be run directly from a flash drive, including LibreOffice programs.
Firefox
is a very nice web browser, also free.
Foxit Reader
is an alternate to Adobe Reader and has a smaller footprint.