LibreOffice Portable is a full-featured office suite -- including a word processor, spreadsheet, presentation tool, drawing package and database
It includes all the tools to replace Microsoft Office or other office suites.
Writer - word processing
Calc - spreadsheet
Impress - multimedia presentations
Draw - graphics and diagrams
Base - Database front end
Math - formula editor
It also supports additional features through extensions
PDF Import
Presentation Minimizer - Reduces the file size of the current presentation
ReportBuilder: To build good-looking database reports
Wiki Publisher : the Wiki Publisher extension lets you create Wiki articles on MediaWiki servers
Read more here
You can get a portable version of LibreOffice from here