Water drops

Create a new document with a dark blue (or whatever color you want your drops to be, make sure they are dark) with dimensions about 500x500. Make a few circles (at least 4) and make them generous in size. The key thing is to make them the same size. You can do this by creating one circle, then duplicating it by pressing Ctrl + Alt + D

Fill one of the circles with a light blue color (sky blue) and put in a drop shadow. The drop shadow can be added by clicking on the circle then going to the Effect Tab, then, in the drop down menu, choosing Shadow and Glow, and then choosing Drop Shadow. You can use the paint bucket and the swatches to fill the circle.

Now, take on of the circles, select it by clicking on it, and expand it to 110% by going to Modify - Transform - Numeric Transform. Type in 110% and then drag the big circle and place it over the sky blue circle. (Notice how the shadow and blue circle are completely covered.

Now we add the gradient to the circle. Go to the Fill tab, and select a radial fill. Change the colors to a light gray and white by clicking on the little pointers (the square with the triangle on top) and selecting the appropriate color. Check out my settings to the left. Now, select both circles: the one with the gradient, and the circle that is under the gradient. Then go to Modify - Mask - Group as Mask.

Now, with the remaining two circles, make a crescent. Select one circle, numeric transform it to 85%. Drag it and put it over the circle like so.

Now, go to Modify - Combine - Punch. You should now have something like the left.

Finally, drag the crescent into the bubble, decrease its transparency or opacity to about 65%, and you're done!