Gray also recommends "The Stick" for getting in areas you can't get with the foam roll. I got the "Tiger Tail" Perform Better.Com and the "Fitball Therapy Ball" http://www.performbetter.com/SearchResult.aspx?rnd=30
The ball works better than a tennis ball for spots that need lots of work, especially the glutes and back.

Both are small enough to pack for travel, including bike tours.