Science has yet to uncover the basis of left-handedness.  Some research suggests that it is related to an anomaly in brain lateralization.  One theory indicates a genetic basis, but another school of thought disputes this, looking at possible developmental issues instead.  Relationships with the immune system and with an excess of testosterone have also been examined.  The latter may be associated with the finding that there are slightly more left-handed men than women.

While science ponders the causes, technology is beginning to address the everyday problems that face left-handers.  Products specifically designed for lefties include kitchen knives with serrations on the right side (most are serrated on the left and thus biased toward righties), scissors, brick-layers' trowels and cake servers, tape measures (try using a regular retractable tape measure with your left hand), corkscrews, computer keyboards (with the number keypad on the left), and boomerangs.  These are not high technology--they didn't require vast investments in R&D to develop.  But they are making life easier for me and Bill Gates.

Links:
= highly recommended

Rosemary West's Left-Handed Page--an excellent resource, with information on art, poetry, humor, books, and products--even a source for left-handed crocheting.

The Left-Handed Liberation Front--you can join it, if you qualify.

Being Left-Handed (or "Living in the Mirror")-- a rather personal look at left-handedness.

Left-Handedness (and other symptoms of a disordered mind)--another personal look at being left-handed, by Janis Cortese.

The Left-Handed Universe--not a huge amount of content, but a fun site (in English, Dutch, and German).  Includes a test to determine how strongly right or left-handed you are.

Playing Violin and Fiddle Left-Handed, a book by Ryan J Thomson ($24.95, order from the site).  "Yes, you can play left handed and be a great violinist or fiddler - it's not necessary to play like a righty!"

Primate Handedness and Brain Lateralization Research, by M. K. Holder, Ph.D.  Holder is a primate researcher at Indiana University and this popular page has a more scientific bent than most left-handedness resources on the web.  Although his online study has closed, visitors can sign up to receive notification of the report when it is available and can complete a short questionnaire regarding public interest in handedness research.

What are left-handed materials?  Here's a clue:  they're not materials for left-handers.  From the physics department at the University of California, San Diego.

An Islamic view of left-handedness, from Islamicity.com, the Global Muslim eCommunity.  Contrary to popular belief, you will not go to hell for using your left hand for eating.

"Study finds left-handers don't die earlier," by Emma Ross, Associated Press, May 28, 1998.  Debunking a study published several years earlier that concluded they did.  Whew.

Left-Handed Products:
       Southpaw Enterprises (Canada)
       LeftiesLine, featuring "the only ergonomically designed left-handed can opener." (US)
       Left-Handed.com, with a wide-selection of products (UK)
       Leftyportside.com, an even larger selection of products (including left-handed cups?!) (US)
       Sweet Pea's Shoppe (US)
       The Left Hand Shoppe at Cybermall2 (US)
       sinErgo--Left Hand Ergonomy (Germany)