This technology trend cross-ruffs with workforce trends: an increasing percentage of professionals are free-lancers, and sourcing sophisticated professional services abroad grows steadily.

FORBES: Virtual Workers Will Disrupt Many Professions

Also called "solo" or "one-participant" 401(k)s, they are available to free-lancers, independent contractors and sole proprietors. as well as business owners with no employees other than a spouse.

WSJ: Conquering Retirement; Savings Plans for the Self-Employed