Incan Gold is a great little game (originally created as Diamant, now in its second edition as the incarnation Incan Gold) where all players are explorers in a ruin. You collect gems in the ruined temple, and decide each turn whether to return to camp. If you do you keep all the treasure you found. If you stay you can get more treasure, but also if you experience two of the same hazards while there you lose everything you found. For a basic game it has great tension and decision making, especially with eight players. This is a top quick game for the younger folk in my family to pull out and play.
Saboteur is another small card game, my wife bought it for me four or five years ago and it can take up to ten players. All participants are either miners who try to build a tunnel by laying cards (in a Water Works-like fashion) to a hidden gold mine, or saboteurs who try to prevent that from happening, As nobody's role is known unless revealed through actions, it is a very interactive game of 'whose on my side?' It begs for multiple plays as gold is received each round you play and roles change.
Both of these games satisfy the 6-8 player range, play very quickly, and require some thought and decision-making that keep it interesting.