Eight-minute Empire is a wonderful game that we've just got. If, like me, you think Risk is too often (read: always) decided by the initial army placement, followed by 2+ hours of grind, 8-minute Empire is its antidote. Enough skill and strategy required that adults can play and not be bored, but the mechanics are simple enough and there's enough luck involved that our 8-yo can play with us and not always end up last.
Love Letter is an intriguing card game. Once said 8-yo got over the name, he really enjoys playing it.
Original Carcassonne (ours came with the Rivers expansion) and Ticket to Ride also get an upvote from me.
More child-oriented fare are: Labyrinth, and Hey! That's My Fish.
If you've got a few spare hours, Wil Wheaton's Tabletop series is on Youtube, and is head and shoulders above any other videos-about-board-games you'll catch on there.
If not, boardgamegeek is a Ronseal-esque forum.