Note 5 - Stock Option Activity (Details) - The 2007 Equity Incentive Plan [Member] - $ / shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Minimum [Member]
Balances, exercise price per share (in dollars per share)	$ 0.22	$ 0.23
Balance, exercise price per share (in dollars per share)	0.22	0.23
Maximum [Member]
Balances, exercise price per share (in dollars per share)	1.89	1.89
Balance, exercise price per share (in dollars per share)	$ 1.89	$ 1.89
Balances, options outstanding (in shares)	10,241,086	8,601,086
Balances, shares available (in shares)	1,758,914	3,398,914
Balances, weighted average price per share (in dollars per share)	$ 0.44	$ 0.44
Expired, options outstanding (in shares)		(200,000)
Expired, shares available (in shares)		200,000
Expired, exercise price per share (in dollars per share)		$ 0.58
Expired, weighted average price per share (in dollars per share)		$ 0.58
Balance, options outstanding (in shares)	10,241,086	8,401,086
Balance, shares available (in shares)	1,758,914	3,598,914
Balance, weighted average price per share (in dollars per share)	$ 0.44	$ 0.43