If you like photography, I found this site very helpful when I started back into photography and still read their articles today.
Many of the serious photographers use this site to keep improving.
Digital Photography Tips: Digital Photography School
Another very helpful source is to join a Photography club. I belong to 4 and I am on the Board of 2 of them so (not that being on the Board is that helpful to developing my photography skills).
The fundamentals of photography are the same.
The differences are the vast flexibility you have with digital compared to film.
You can blast away but I have learned to slow down and take my time and concentrate on one good shot rather than 50 so-so shots.
Take your time and think about what you are doing. Get high, get low, go left, go right, move back, move forward. Perspective is what separates the good images from really good images.
Another thought is that with Digital, the shutter click is just the beginning.
Today, you will be creating images rather than taking a picture.
Buy Adobe PhotoShop Elements 10 and use it ... really use it.
One's ability to use Elements (or Photoshop or Lightroom) is critical to getting sharp and saturated colors with a digital image.
All digital cameras (except the Nikon D800e) have filters in them that make the images look dull and lifeless.
Shoot RAW if your camera supports it and jpg.
Note: The jpg out of the camera already has some sharpening, contrast and saturation applied to them so these are not the "dull and lifeless" images I am talking about.