On the subject of amateur adventure games... Scurvyliver's That Night Before (http://scurvy.adventuredevelopers.com/tnb.html
) is still my favourite of all time. It's full of LucasArts references and injokes and it's more fun than sex on a bicycle.
As to the last adventure game I played: Sam & Max S.2 Ep.4 -- unless Baldur's Gate II counts!
Actually, scrub that, I played that 2D one room Strongbad flash adventure game, which was really awesome.