OEM Accessories, Parts and Literature
H and A Accessories
Bernardi Parts of Natick, Mass. Newly designed site (November 2015) is much less useful.
Hondaautomotiveparts.com by Majestic Honda of Lincoln, R.I.
College Hills Honda of Wooster, Ohio
HondaPartsDeals.com by Saccucci Honda of Newport, R.I.
Honda Parts Now by Robertson Honda of North Hollywood, Calif. Part-number search returns include model fitment.
Helm Inc.: Owners manuals, service manuals, etc.
Honda Service Express: Tech literature, TSBs, etc., mostly in PDF format. Paid subscription ($20, $50, $500).