USA Payroll has found these web sites to be helpful.

Federal
Internal Revenue Service	http://www.irs.gov/
Social Security Administration	http://www.ssa.gov/
US Department of Labor	http://www.dol.gov/

New Jersey
NJ Division of Taxation	http://www.state.nj.us/treasury/taxation/
NJ Department of Labor	http://lwd.dol.state.nj.us/

Pennsylvania
PA Department of Revenue	http://www.revenue.state.pa.us/
PA Department of Labor and Industry	http://www.dli.state.pa.us/
Act 32 EIT Collection System	http://www.newpa.com/act32/

Delaware
DE Department of Labor	http://www.delawareworks.com/

Philadelphia
Philadelphia	http://www.phila.gov/