Just wanted to share my recipe for a great smoothie/shake for pre or post-workout or any time of the day for that matter:
I use water as a base and throw in about a half cup of orange juice for some flavor. I add a cup of oats, 1-2 scoops of protein, a banana or an apple, some frozen fruit, about a cup or 2 of spinach (you can use as much as you want and won't be able to taste it), and half a cup of egg whites. Depending on the flavor you can also add some organic peanut butter...
I throw it all in the vitamix and use the preset smoothie function and it's pretty much perfect. Really easy to make and it tastes great too.