This maybe is more trouble to implement than it’s worth, but I think of how Github (was it them? or somebody else?) recently implemented a “like” system because so many threads were getting clogged with “me too” responses. I just felt the temptation to merely second somebody’s recommendation of a resource—“Oh yeah, I love that one!”—but restrained myself. I’ve seen forums where that kind of response is banned and/or discouraged through reminders and interaction, but the “like button” might be a more elegant solution.
There is already a like button.