A good rule of thumb is you should be able to bench your body weight for 12 reps, which I assume is roughly equivalent to 4 sets of 10 reps (with a 1-3 minute rest between sets? I guess it would not be as impressive if you rested an hour or more between sets!). However if you can do that you are probably in the top 1% of the population as a whole and the top 5% of people who work out regularly. Don't forget to do squats, deadlifts (150% of body weight for 12 reps), bent rows and pull ups (body weight for 12 reps) as well to keep yourself symetrical and prevent injuries! Hand stand pushups (body wieght for 10 reps) are another excellent exercise requireing strength, balance and coordination to demonstrate your fitness level.