I'm live in a major metropolitan area, so these tips may not work (or even make sense) for everyone:

• Ride along a route with or near public transporation: If your bike fails, just hop on the train or bus, and let them get you close to your destination. Or hail a cab, put your bike in the trunk, and have the driver take you to the nearest LBS.
• Double-lock your bike: If your destination has public bike parking only, use two totally different security systems to lock your bike. Secure the cable or chain such that it will not move, and fill as much the space within the lock as possible.
  
  As an example, I use a braided steel cable going through the entire bike, with a padlock going through the cable loops and seat. The second lock is a short chain with enormous links and a small U-lock. I wrap the chain through the frame and real wheel, then send the lock through the chain links and the frame.

On lights: As an electrical engineer and amateur photographer, I must point out that the Watt is unit of measure for physical power. Watts can tell you how much power a light may consume, but its cannot tell you exactly how "bright" the light will be. For example, a 100 W incandescent light bulb may appear brighter or darker to the human eye than a 100 W halogen light bulb, depending on bulb type, fixture/enclosure, etc.

A far more useful unit of measure for light power or "luminous flux" is the lumen. The lumen will tell you how bright something appears to the human eye. Most packaging for household light bulbs have the number of lumens printed on the box. Cycling light manufacturers really should do the same.

Steven Scharf's website elaborates more on this from a cycling perspective.