M.F.
I ordered these last season and they were a big hit!
http://www.personalizationmall.com/Personalized-All-Star-...
There were 3 coackes and I think I said something like "Thank You Coach <coach name>" on each one and selected the soccer balls for the design. When they arrived, we had all the children sign their names with a metallic sharpie.
If you want to get really fancy and you have the team photo, you can also do a photo mug with some words on it also.