Here's the Blackwater page for the most recent complete fiscal year, which was 2006:
http://www.fedspending.org/fpds/fpds.php?reptype=r&detail=-1&sortby=f&datype=T&reptype=r&database=fpds&database=fpds&parent_id=38113&fiscal_year=2006&record_num=f500By changing the search criteria, you can get other years and contract-by-contract detail, but here are some of the summary figures. You'll see that the Department of State is by far their largest customer -- since it uses Blackwater for bodyguard services -- followed by the immigration guys (which is pretty scary in itself.) The military pays comparatively small amounts, mainly for use of Blackwater's training facilities.
Top 5 Contracting Agencies Purchasing from Contractor(s)
STATE, Department of $489,208,052
Bureau of Immigration and Customs Enforcement $73,152,050
NAVY, Department of the $14,067,651
AIR FORCE, Department of the (Headquarters, USAF) $7,250,186
U.S. Special Operations Command $4,884,426
2000 $204,911
2001 $736,906
2002 $3,415,884
2003 $25,395,556
2004 $48,496,902
2005 $201,010,119
2006 $593,075,845
2007 2Q* $187,297,239
*Note: FY 2007 only includes up through second and part of third quarter.