There are a huge variety of exercises you can do with pushups and pullups just by varying grips and body position. Some might say that your strength gains are going to be relatively modest with bodyweight exercises. However, you can very easily tailor your routine for strength IMO. If you can do...
- 5 one-armed pullups with each arm
- 10 unassisted handstand pushups
- 5 one-armed decline pushups with your feet up on the bed
- 10 pistol squats with each leg
...then I think you have a lot of strength. Not enough for you? Then add a 50lb weight vest and try again.