Here are links to some useful bike related sites. Most of these are online shopping sites for motorcycle parts and accessories, but there are a few invaluable sources of information here as well.

Shopping sites
M and P clothing, spare parts, accessories, upgrades, books and just about anything bike related.
M.P.S. clothing, spare parts, accessories, upgrades, books and just about anything bike related.
Hein Gericke mainly clothing, accessories and upgrades.
Busters clothing, spare parts, accessories, and upgrades.
Morgan Carbtune The people who make the Carbtune vacuum gauges. There is also plenty of information showing how to use their gauges to balance your carbs.
Forest Edge Retail These guys specialise in selling items from the "Oxford Products" range of clothing, luggage and accessories.
H.E.L. Manufacturers of Stainless Steel Braided Hydraulic Hoses.
David Silver Spares Genuine Honda replacement parts.
Pattern Parts.net As the name says, they sell pattern motorcycle parts.
Infinity Motorcycles A leading supplier of motorcycles and motorcycle accessories
Honda Hornet Sites
Honda Motorcycles The official Honda UK Web Site.
The Hornet's Nest If you already own a Hornet, or are thinking about buying one, then you have to look at this site. It is the home of the "Honda Hornet Owners Club" and is the best place I have found to get information about the Hornet online. Club members get exclusive access to lots of technical information about the bikes, and are also entitled to discounts from quite a few retailers for parts and accessories. This makes it is well worth joining, especially if you are thinking about making any modifications to your machine.
The Hornet's Nest Message Board This is the main area of activity in the club and it is always full of friendly people who are keen to help answer any questions.
Other sites
M.C.N. The MotorCycle News web site.