I'm so glad you asked, @mianguyen, because I happen to think bruschetta is the best impromptu appetizer ever. For purposes of this list, I'm going to allow bruschetta to mean bread topped with stuff.
  1. Classic tomato and basil
    Toss together 3 chopped ripe Roma tomatoes, 2 clove minced garlic, a handful of fresh basil leaves, chopped, 2 tbsp good extra virgin olive oil, a touch of lemon juice, salt and pepper. Let sit for at least 20 minutes. Grill or toast slices of baguette, then rub bread with a clove of garlic to season. Spoon tomato mixture over the bread slices.
  2. Pear, gorgonzola, and caramelized onions
    Top grilled or toasted baguette slices with a couple of thin slices of fresh Bosc, Bartlett, or Anjou pears, a crumble or two of Gorgonzola or other blue cheese, and a pinch of caramelized onions. Top with lots of black pepper.
  3. Greek
    Make classic bruschetta as described above, except use parsley instead of basil, and stir 1/4 cup of crumbled feta into the tomato mixture and top each bruschetta piece with a pitted Greek olive.
  4. Lox and creme fraiche
    Top toasted baguette slices with creme fraiche or sour cream, thin slices of lox, slivers of red onion, capers, dill, and a squeeze of lemon. Top with black pepper. Boom. It's reminiscent of bagels and lox, and you can serve it with cocktails.
  5. Goat cheese, fig and prosciutto
    Top toasted baguette slices with a smear of goat cheese, a dollop of fig jam or, when they're in season, a slice of fresh fig, and a twirl of prosciutto.
  6. Pesto-artichoke
    Spread prepared pesto on toasted baguette slices, then top with sliced artichoke hearts.
  7. Cream cheese and red pepper jelly
    Top baguette slices with a thick smear of cream cheese and a teaspoon or so of red pepper jelly (this kind from TJ's is good: www.traderjoes.com/fearless-flyer/article/1427). Top with black pepper.
  8. Cream cheese, Nutella, and toasted hazelnuts
    Brioche or challah toast, smear of cream cheese, drizzle of Nutella, shower of chopped, toasted hazelnuts.
  9. Make sure to pronounce it broo-SKETT-ah. Hard "sch"
    Suggested by @corey