These first two are a picture of my eyes that I took. I took the line tool and drew a series of lines on it in a pattern i liked. I used the measures on the sides of the screen to make sure everything was even. After that I selected areas and colored over it. I did this a few times, overlapping areas to make areas darker.
Abstract....at first it was supposed to be balloons or balls but it reminds me of clowns now. =] Basically I took a blank window and drew different size circles all over and colors them in either blue, red or yellow. I think these colors compliment each other well. I then selected the insides of the circle and made them a shade or two darker and feathered out the edges with the blur tool.