most current ATV laws by state:
Alaska
http://www.state.ak.us/local/akpages/ADMIN/dmv/reg/snow.htm
Alabama
http://www.ador.state.al.us/motorvehicle/Registration_FAQ.html
Arkansas
http://www.fs.fed.us/oonf/ozark/recreation/ohv.html
Arizona
http://www.gf.state.az.us/pdfs/outdoor_recreation/atv_brochure.pdf
California
http://www.dmv.ca.gov/vr/offhighway.htm
Colorado
http://parks.state.co.us/default.asp?
Connecticut
http://www.cga.state.ct.us/2002/olrdata/tra/rpt/2002-R-0807.htm
Delaware
http://www.dmv.de.gov/Vehicle_Services/Special_Vehicles/ve_spec_off_highway.html
District of Columbia
http://www.svia.org/InfoSheets/StateReq_0803.pdf
Florida
http://www.fl-dof.com/Recreation/OHV/OHVlaws.html
Georgia
http://georgiamagazine.com/outdoors/nf/atv/
Hawaii
http://www.svia.org/InfoSheets/StateReq_0803.pdf
Iowa
http://www.iowaohv.com/04registration.htm
Idaho
http://owyheecounty.net/recreation/motorbike-atv-laws.htm
Illinois
http://www.svia.org/InfoSheets/StateReq_0803.pdf
Indiana 
http://www.in.gov/dnr/outdoor/ohv/ohvfaq.htm
Kansas
http://www.svia.org/InfoSheets/StateReq_0803.pdf
Kentucky
http://www.kytc.state.ky.us/drvsmrt/atvlaws.htm
Louisiana
http://www.svia.org/InfoSheets/StateReq_0803.pdf
Massachusetts
http://www.mass.gov/dfwele/dle/instructionspage.htm#ATV
Maryland
http://www.dnr.state.md.us/publiclands/orv.html
Maine
http://www.state.me.us/ifw/rv/atvlaws2004.htm#Operating%20unregistered%20ATV
Michigan
http://www.michigan.gov/dnr/0,1607,7-153-10365_15070-73699--,00.html
Minnesota
http://files.dnr.state.mn.us/rlp/regulations/ohv/ohv2003_legbrief.pdf
Missouri
http://www.svia.org/InfoSheets/StateReq_0803.pdf
Mississippi
http://www.svia.org/InfoSheets/StateReq_0803.pdf
Montana
http://www.doj.state.mt.us/driving/vehicletitleregistration.asp
North Carolina
http://www.svia.org/InfoSheets/StateReq_0803.pdf
North Dakota
http://www.ndparks.com/trails/atv/atvlaws.htm
Nebraska
http://www.nohva.com/atvtitling.htm
Nevada
http://www.dmvnv.com/newresident.htm
New Hampshire
http://www.wildlife.state.nh.us/OHRV/ohrv.htm
New Jersey
http://www.state.nj.us/mvc/atv/atv.htm
New Mexico
http://www.abqtrib.com/archives/news03/110703_news_atv.shtml
New York
http://www.nydmv.state.ny.us/broch/c29.htm
Ohio
http://www.northeasttrailriders.com/laws.htm#revised_code
Oklahoma
http://www.fs.fed.us/oonf/oklahoma/hike/orv.html
Oregon
http://atv.prd.state.or.us/permits.php
Pennsylvania
http://www.dcnr.state.pa.us/forestry/atv/registration.aspx
Rhode Island
http://www.svia.org/InfoSheets/StateReq_0803.pdf
South Carolina
http://www.svia.org/InfoSheets/StateReq_0803.pdf
South Dakota
http://www.state.sd.us/drr2/Howto/register.htm#Off-Road%20Vehicles
Tennessee
http://www.svia.org/InfoSheets/StateReq_0803.pdf
Texas
http://www.southernregion.fs.fed.us/texas/recreation/orv_info_ang_dc_sab.shtml
Utah
http://www.stateparks.utah.gov/ohv/registering.htm
Virginia
http://www.svia.org/InfoSheets/StateReq_0803.pdf
Vermont
http://www.aot.state.vt.us/dmv/REGISTRATION/ATV/ATVs.htm
Washington
http://www.svia.org/InfoSheets/StateReq_0803.pdf
Wisconsin
http://dnr.wi.gov/org/caer/cs/registrations/ATV.htm
West Virginia
http://129.71.164.29/Bill_Text_HTML/2004_SESSIONS/RS/House/H_BILLS/hb4022%20enr.htm
Wyoming
http://wyotrails.state.wy.us/trails/atv.htm