I've actually wondered about that myself. Instead of aerating the wort with a pump or pure oxygen, just set the fermenter on a stir plate for a couple of hours.
Oxygenation is only a problem after the yeast have completed their adaptive phase, ~4 hours. Assuming the stir bar has enough surface area and torque to cause a small whirlpool, it should work.
And interesting experiment would be to:
- Brew a medium gravity batch of hopped wort.
- Split into two large flasks and pitch equal amounts of yeast.
- Aerate one flask with an aquarium pump.
- Place the other flask on the stir plate for ~2 hours.
- Wait 5 days.
- Measure final gravities and conduct a taste test.
- Repeat, this time with a high gravity wort.