The United Nations just released its 2013 report on world murder rates (UN Office of Drugs & Crime). It includes over 160 pages of color-coded charts and statistics detailing country homicide numbers (per capita), types of weapons/instruments (guns, knives, other agents), annual changes, etc.
The Americas (North, Central, & South) now show higher murder rates than Africa in certain categories. Lichtenstein had the least homicides (with zero murders in 2012), and Honduras had one of the highest murder rates. Asia showed relatively low suspect conviction rates.
The report is highly informative and probably contains more information than the average person needs to know about world homicide statistics.