Woodcutting definitely would be the easiest low-effort 99 other than cooking and fletching in my opinion.
OFF TOPIC: That's what sort of happenned to me. Got caught up in Mw2, Borderlands, Assassin's Creed 2, Dragon Age, and Left 4 Dead 2. With Mass Effect 2 coming out tomorrow, idk if i'll ever get much done on RS.