I've only seen the "take 10" specifically disabled for ritual checks (PH1, p. 300). Are they allowed for Aid Another?
Technically yes, in practice usually no
From the RC, p127:
Nothing in that list forbids you from taking 10 when you aid another. It does, however, ban taking 10 in most of the situations in which you would actually want to use the aid another action, skill challenges in particular.