I read many primary texts and since I focus on Sanskrit philosophy, they are by rule immediately able to let me look at old questions with new eyes (e.g., in the case of the epistemology of testimony), or to ask new questions altogether (e.g., how can an atheist school of thought accommodate belief in God?).
I get the same feeling whenever I am able to go back to Western texts with some distance, for instance, because they are chronologically, thematically or stylistically far away (e.g., reading Orthodox theology, or Augustine's dialogues, or some of Derrida…). With new questions and new ways to look at the world, I never had the problem to look for new ideas, rather, I have often the feeling of having too many for a single life (which does not mean that they are philosophically sound).
Discussing with colleagues and friends is also a constant source of inspiration.
UPDATE: I once asked this question to a senior and learned colleague, who seems to share my feeling, since he answered: "I do not look for ideas, they pursue me!" and then added "If this is not the case, just quit!".
What about you? Do new ideas follow you, no matter where you try to flee? Or do you actively look for them? And where?
This paper has been triggered by this one on the Philosophers' Cocoon.