Social liberalism
Interestingly enough, Isaiah Berlin, perhaps the most important social liberal of the 20th century, claimed that liberalism was "merely a watered-down version" of anarchism, with both based on the premise that equality and liberty are compatible. I think it's fair to say that many social liberals (though not all) aren't opposed to the ideal of anarchy, which they hold up as a shared ideal, but merely doubtful as to its feasibility, whether or not it would be possible to implement such an extreme form of equality-liberty.
Given the fact that anarchism, for all intents and purposes, emerged as a synthesis of socialist and liberal ideas, whilst social liberalism is, as the name suggests, the introduction of a more social element to liberalism (remember, by the way, that Berlin was not a supporter of the Liberal Democrats, but of the Labour party), I don't think it's unreasonable to suggest that anarchists and social liberals are on the same basic line of the spectrum, with the difference being anarchists' belief in the possibility of a more 'extreme' (or complete) version of equality-liberty than their somewhat more cautious counterparts, nor is it particularly surprising.
As such, my thoughts are that social liberals are definitely worth paying attention to (particularly their thinkers, some of whom offer ideas which are of great value, if implemented into an anarchist critique; having mentioned Berlin, I could cite his value pluralism as an example), and perhaps constitute a pool of potential anarchists, who need not be convinced of anarchy's desirability, only its feasibility, and the inability of social liberalism to maximise equality-liberty, the aim they have set for it.
