Assured Lock has a huge online catalog of locks for every imaginable need... cabinets, drawers, doors, windows, and even mailboxes! (They even carry the hard-to-find Kaba Ilco locks commonly used on apartment mailbox units.) If you're looking for a new or replacement lock and can't find it locally, try here first!
GoKeyless.com features a full line of keyless security products, from non-electric mechanical deadbolt locks to biometric, fingerprint and thumbprint locks. These sturdy, high quality locks are fairly easy to install for the do-it-yourselfer and come with an exclusive 30 day return guarantee from GoKeyless.com in addition to the manufacturer's warranty.
Baldwin has manufactured top quality 100% brass locksets, lamps, outside light fixtures, switch plates, bathroom accessories and more for over 50 years. The caliber of their website matches their products, with top quality troubleshooting of their locks and installation help. Even if you're never lucky enough to own a Baldwin, this link may be valuable for a "friend" in need!
If you are looking for information about home security, pad locks, gun locks, and various other security devices, Master Lock Company is the site to visit. And if you have lost the key or forgotten the combination on an old Master combination or keyed lock, they may be able to help you!
Schlage Locks are by far NH's favorites... for real! Schlage locks are made strong but trim, so that they can be easily retrofit into your old door. Their site has installation instructions (helpful for maintenance if you own a Schlage but didn't install it yourself), great home security tips, and (of course) an overview of their product line.