I have thought about making video tutorials on how to use Photoshop to create practical design elements. Ie, how to make a button or how to design a header. Something every programmer making their own webapp could use that doesn't really require much Photoshop knowledge.
Don't underestimate the value of layer styles. In fact I would say that for most UI design 80% of the "visual style" can be achieved via layer styles.
Just make sure to Name and Group your layers, otherwise you can end up with 100s of layers named Layer N with undecipherable thumbnails. Also it's nice to save your most commonly used layer styles to swatches.
Absolutely. I'd also recommend the tutorials at Lynda.com for really in-depth overviews - they have a whole set of tutorials focused on web design with CS5: http://www.lynda.com/home/ViewCourses.aspx?lpk0=116
That said, Lynda.com is subscription-based and tends to be lengthy. A short set of tutorials on key techniques would be a great resource.
I would be interested in a set of tutorials on buttons, drop shadows, torn paper effects, header design, logo design text effects - all of the stuff that I use or need to use Photoshop for.
Would there be any interest?