I am a huge fan of open source products, and find many compete quite favorably with commercial offerings.  Because  open source software is either inexpensive or free, students can obtain multitudes of new tools that they otherwise could not afford.  To my delight, I recently discovered a free e-book entitled Free Software for Schools by Open Source Victoria.  This handy book lists dozens and dozens of useful open source software products  categorized by genre as well as operating system.  I found the  free .pdf version  quite satisfactory, but if you prefer a printed book, you can order your copy from the publishing-on-demand service, Lulu.com, for around $20.00.