Strobist is excellent. It got me started and there's night and day difference between my photos then and my photos now. Come to think of it, when I first started, I had no desire to shoot people and now that's probably my favorite part.
Any ways, you're talking about lighting modifiers. Soft boxes, umbrellas, reflectors, snoots, grids, barndoors, and anything else like that are just modifiers.
I usually use umbrellas with my speed lights. When I finally get decent space for a studio, I'll pick up a set of lights and start using softboxes. The problem with trying to use a large softbox is that it takes a lot of light to light one. Most of the big ones (about 2'x3' or bigger) that I've seen people use with speed lights are usually lit by two speed lights to get enough light to make one useful. But then again, trying to use a softbox in a field with a studio strobe that's not ran on AA's can be an endeavor.
It all comes down to practice.
Also, the strobist site explains what those modifiers do and shows examples and how to use them. The rest is just up to you and your creativity.
I did some film noir shots with two strips of duct tape over the flash head, limiting the light to about a 3"x 1/2" slit. It created an extremely hard light and turned out perfect. $0.02 worth of material based on an idea and some knowledge from strobist.
I think the biggest thing to do at this point if you're interested in lighting is to learn how it works and how to control it. Whenever I shoot, I tend to visualize the shot I want and then setup the lights with all appropriate modifers to attain that vision. It's not spray and pray.
www.strobist.com
Also, pick up "Light Science & Magic" by Phil Hunter. It's an
excellent book that teaches how light works and not "where to put your strobes for this picture", and will get you on the right track.