HappyAnika,

tha's basically what I've been doing. I use products from these people (no connection, just grateful muscles):

http://www.tptherapy.com/quad%20baller%20.php

I use the quadballer to roll my quads on and my IT band (they have demos on the site) though I feel like a bit of a contortionist when doing it. I also use the little ball thing to pinpoint other areas and to roll across the IT band - it hurts like hell. The ball thing is "good" got the piriformis too. It is almost like a human thumb but is not as good as a proper massage but good to use inbetween massages. I also have the footballer for my calves which is good for the achilles but I find myself using the little ball more as its easier to pinpoint certain areas.

The TP site has lots of pictures on how to tackle various muscle groups with the ball and the roller, the little ball is definitely the most versatile and I'm sure a tennis ball is a reasonable stand in.