Updating the information from last year, the four best ride calendars that I have found are:
Tandem Club of Americahttp://www.bkspeck.com/tca/rides.cfmTandemLink.comhttp://www.thetandemlink.com/RallyInfo.htmlTailwind Tandem Clubhttp://www.tailwindtandemclub.com/links.htmT-Bone (Tandem Bicyclists of New England)http://www.tbones.net/Rides/rides.htmSeveral nearby rides this year will be:
Tandems East Tandem ExpoThis is not a ride, but a show and mini-conference, attended by some of the big names in modern tandems. Test rides will be available.
3/29 & 30, Centerton, NJ (~7 hrs from Burlington)
http://www.tandemseast.com/events/expo.htmlSt. Michael's Weekend4/18-4/20, Chesapeake Bay, MD (~9.5 hrs from Burlington)
http://www.bikepptc.org/node/1198Canadian Tandem Rally 2008May 23-26, Gananoque, Ontario, Canada
(~4.5 hours from Burlington, VT)
http://www.mbstandems.com or
http://www3.sympatico.ca/vandevelde/rally/index.htmlMATES 20086/13-6/15, Flemington, NJ (~6.5 hrs from Burlington)
$210 per team, 4/1 registration deadline
http://www.easterntandemrally.orgTandems East Tandem Weekend6/27-29, Pennsville, NJ (~7.5 hrs from Burlington)
http://www.tandemseast.com/events/weekend.html$495 per couple, 45 & 60 mile rides
Eastern Tandem Rally8/1-3, Durham, NH (~3.5 hrs from Burlington)
http://www.easterntandemrally.orgSouthern Tier Tandem Rally8/22-24 ($30-$65 per team, 7/1)
Elmira, New York (~6 hrs from Burlington)
http://www.gtgtandems.com/sttr.html2008 Weekend in Lancaster9/26-28, Lancaster, PA (~8 hrs from Burlington)
http://www.baltobikeclub.org/index.pl/bbc_eventsThere are also three off-road tandem events in the region
Eastern Off-Road Tandem Rally4/4-4/6, Batsto, NJ
http://www.dscb.org/etr/etor08.aspFall Alleghany Rally for TandemsSalamance, NY
10/3-10/5, Salamanca, NY
http://homepage.mac.com/bmanagan/fartThis one looks like great fun, if you have an off-road tandem.
Tandems Off-Road at Minnewaska-Mohonk10/31-11/2, Gardiner, NY
http://www.dscb.org/etr/dogs_or.asp