Go to the home page of this website and read the articles listed in the left-hand column. With the aid of those I was able to reduce my total pack weight for a 9-day trip from 50 lbs. to 25.

You don't have to spend a lot of money, either (except maybe for a top quality sleeping bag). Here are some ideas. If you browse through the "Lite Gear Talk" section of this forum, down a ways (December) is a thread on "$200 and 20-lb. challenge." Also check the Archives, especially the 2005-08 section (see left hand column of this page).

The main requirements are a computer spreadsheet (I assume you have the software for that since you're on a computer!) and a digital postage scale that weighs in 0.1 ounce increments. List everything you have and its weight and compare to the lists of others who hike in similar conditions. I still use my spreadsheet to evaluate possible new gear purchases (as Glenn says, gear shopping can be addictive!) and, most important, to print out a checklist when preparing for each trip.