This is one of those shocking lists that shows how exploitative the US system of labor is.
Legally required minimum leave by country:
Australia As of 27 March 2006, 20 work days (4 weeks). 2 weeks can be "sold" to employer. Additional Long service leave is also payable. 10 public holidays as well are payable to employees.
Austria 5 weeks
Belgium 20 days, premium pay
Brazil 30 consecutive days after 1 year employment, of which 10 can be sold back to the employer
Bulgaria 20 working days
Chile 15 working days
Colombia 15 working days for every year, vacations can be accumulated for up to 4 years (up to 60 working days of vacations)
China 11 working days.
Czech Republic 4 weeks
Denmark 25 work days
Estonia 28 calendar days
European Union at least 4 weeks, more in some countries
Ecuador 14 days
Germany 4 working weeks
Greece 20 working days or more depending on the years in the company
Guatemala 2 working weeks
Hong Kong 7 days
Hungary 20 working days (increasing up to 30 with age)
Iceland 24 days, not including 13 official holidays.
Iran 4 weeks
Israel from 10 working days for the first year to 24 days for 14-th year and on, not including official holidays, sick leave, etc.
Italy 20-32 working days (exact amount depends on contract details), plus 12-13 public holidays.
Kazakhstan 24 calendar days
Latvia 4 weeks
Lithuania 28 calendar days 
Netherlands 4 weeks
New Zealand 4 weeks as of April 1, 2007, plus 11 paid public holidays.
Norway 25 working days
Pakistan 15 working days
Paraguay 14 days
Peru 14 days
Portugal 22 working days, up to 25 without work absences in previous year.
Puerto Rico 15 days
Russia 28 calendar days, plus 12 public holidays
Saudi Arabia 30 days
South Africa 21 consecutive days
Spain 30 calendar days
Sri Lanka 28 Working Days - 14 Maximum Annual, 7 Casual and 7 Sick Leave 
Sweden 25 work days minimum
Switzerland 28 calendar days (= 20 work days)
Tanzania 28 calendar days
Turkey 12 work days
Tunisia 30 work days
Ukraine 24 calendar days
United Kingdom 5.6 weeks (28 work days), including 8 public holidays
United States none
US law does not require employers to grant any vacation or holidays and about 25% of all employees receive no vacation time or holidays.
See the complete list here.