Hophornbeam is excellent wood for bows...especially when using small diameter saplings. The back can be crowned without much danger of splintering. It's a lot like osage, but stiffer (less flexible), harder, and with less knots. Also, if you like the look of bark on the back, HHB is a good choice (just rub off the outer "scales").
If you plan on making a lot of HHB bows, make sure you have an easy way to sharpen your tools....it's REALLY tough wood when dry.
I'd like to make some more bows from HHB but right now I'm concentrating on juniper (which is almost the exact opposite of HHB in terms of characteristics).