On my first day I was taught this technique for chopping peppers, and I've used it ever since. It's simple to do, takes a couple of seconds, and you use every part except for the seeds and stalk.
Firstly, chop the top off the pepper, from just where the side turns into the top.
Use your hand to grab onto and scoop out the large lump out of seeds in one go.
If there are the odd couple of seeds left inside, holding the pepper upside down and giving it a quick tap on the bottom will flush them out.
Next, pull the stalk from the top part of the pepper.
Now the top and body of the pepper are seedless and ready to be sliced or diced, and all you have to throw away are the seeds and stalk.
Give it a try the next time you're chopping peppers and you'll be surprised how much of a difference it makes, and how much more you'll get out of every vegetable.