Yes....this is a technique that has been around for awhile....not too many people know about it for some reason, hopefully I'm here to change that.
About 3 weeks into the bud cycle, you simply pinch about 1/16 of an inch off the tip of the bud(s). Grow out your thumb and middle (or index) finger nails to pinch the buds with. It kind of needs to be a blunt trauma, so don't use scissors or clippers. If you have a lot of plants, keep a bottle of rubbing alcohol and some cotton swabs to clean the accumulation of resin on your fingernails.
The trick is to pinch the tips off of EVERY SINGLE bud site. This means, anywhere a little nugget is forming off the main branch...every single bud site....needs to be pinched in this manner.
This is a VERY labor intensive process, as you can imagine...especially if you are doing a "tree style" grow.
Repeat this same pinching process about every two weeks....and your buds will get absolutely MASSIVE. The pictures you see of HUGE, FAT buds on websites and in magazines have been pinched...I can almost guarantee it.
A product used by alot of professionals, that not many people know about is called "Pot O' Gold"....made by a company called HydRx. You might be able to buy it at your local hydro shop....if not, you can order it online. I don't know, scientifically what this product does, but I believe it makes your plants drink more water....or perhaps it makes the water more usable by the plant. EITHER WAY....it works...and it makes plants, and buds grow much faster, and larger. It is a trusted product by the pros, and simply mixes with your current fert/water regimine.