Nice thread Im one of the guys you mention, the nice guy to shy to make the first move. In school I always tell myself that Ill talk to this girl and that but when it comes time like when were leaving class Ill make any excuse imaginable to avoid putting myself on the chopping block. One time its "she looks like she doesnt feel like talking" or the most common one "oh no people are around theyll watch me approach her" and that completely ruins my self esteem thinking that someone is going to giggle to themselves and think oh that boy is hittin on her. And of course there is always the fact that if she blows me off well then I get to have the awkwardness of being in class with the girl. ugh I just want an easy button =[.
My two cents would be to just catch there eye and with nice relaxed persona just give a smile and look away. Many times I get multiple looks from them after this but a girl would have to be very interested to approach a guy first. They can have anyone after all.