I have seen some questions that cover subjects with which I am not very familiar but would like to be. Often in these threads, I find a reply which I am unable to judge the accuracy of on my own. In these cases, I would be willing to abstain from voting on the node in order to learn its reputation.
I think this feature would make sense for two reasons. First, the reputation provides some meta information that I could use to better judge the quality of the node and thereby increase my knowledge on the subject. Second, by abstaining, I could avoid polluting the reputation of a node about a subject in which I lack expertise thereby generally increasing the usefulness of the reputation system.
To be clear, I am suggesting that abstention would be a permanent decision. You could not choose to abstain and change your mind later. As I see abstaining as a choice not to vote I don't think it should decrease your votes for the day nor do I think it should have any effect on experience.
I have no real idea whether this would be easy to implement but I suspect it would be.
-sauoq "My two cents aren't worth a dime.";