Instead of just inventors, you can do top 10 lists of artists, athletes, politicians, etc. Just about any profession!
At my school, the 4th grade does research on one famous African-American, past or present, then make a poster about him or her, complete with pictures, trivia and sometimes even the background reflects the person (a boxing ring for Muhammad Ali, a running track for Jesse Owens, a microphone for Oprah Winfrey, etc.). After giving their oral reports (where they actually dress up as their person), the posters are hung up on the board and the walls in the hall. Everyone loves it!