I absolutely love using wax to decorate my eggs. Most egg-dying packets even come with a wax stick specifically for that purpose. You can do nearly anything, like create a nice cloud scene (and a Mario Brothers egg to match the aforementioned egg because the cloud scene reminded you so much of Mario Brothers 3).
It doesn't have to stop at wax sticks. Any type of crayon works wonderfully. Mix the colors to make whatever scene you'd like.
Or you can make a typical "Easter Egg" (like the kind you see in *every* decoration that uses pictures of Easter Eggs) in no time flat.
Or you can do what my husband did and make a Donald Trump egg (or Conan O'Brien egg…jury's still out on that one).
Masking tape is also a great way to enhance your eggs. Lay out strips of masking tape on a cutting board and use a box cutter to create slim slips. You can put the masking tape on first, or dye your egg one color, let it dry, use the masking tape, and dip it in a second color (you can create a pretty awesome watermelon with this effect).