Thanks Dennis for advice, next time I'll go lower and shoot from the ground to get the eyes.
I've thought to give away some 4x6 prints, and at the time ask the parents what they'd like the CD to print themselves or order prints from me.
Genna, all I can say is to fight the urge to give away your prints if you have any thoughts of selling anything to these same parents later. By charging a fair price for your work, you are establishing yourself as a serious photographer in their eyes, and when/if you choose to market a CD to them later, it will be MUCH easier to charge for it.
People just starting out frequently feel uncomfortable charging for their work, especially if it's to friends or other parents, but think about this: could the other parents have taken the shots you did? Probably not. You have the skills and equipment that are worth more than free, so you should establish this up front.
You're probably going to ask what is a typical fee for a game's worth of images? Honestly, even when I was in my first year of shooting it would have not been unusual for a team to pay me $350 for this, and now it's more than this. What they get for this money is a guaranteed minimum 5 "magazine quality" action shots of each player (providing the kid actually plays - if not, I get the player on the bench, or in warm-ups etc), professionally edited and suitable for printing up to poster size. With each team having around 20 players (more for football, for which I charge more), this works out to only $20 or so per player, which if you think of it, really isn't bad at all.
Anyway, this is probably more than you wanted to know, but in summary, don't be afraid to charge for even the initial prints. If $8 or even $5 seems too much, charge $3...