Do any adept powers cost actions? I've been scouring the rulebooks and forums all night for a solid ruling and I can't seem to find anything. The main cause for my concern is Boost Attribute...there's a skill test and drain resistance, which seems to me there's enough effort involved to warrant some kind of action being expended...but I'll be damned if I can find it anywhere.

Aside from those explicitly stated or those for which it's obvious none is required, does using an adept power cost any actions during combat? If so, is it a Free, Simple, or Complex action?

SR4a pg. 195 (under Attribute Boost end of 2nd paragraph)

Attribute Boost requires a Simple Action to activate.

One of the many things not covered by SR4 errata..
Anniversary edition: compliance is mandatory.

Attribute Boost: the only power in the game that gets worse the more ranks in it you buy!