Hello,
Here is an example of the circle drill at our school. We believe it is a great training method to develop feeling and build reflex.
The person in the circle has to use Wing Chun techniques, while the attackers choose from a handful of combinations/techniques of any style to attack. As the defender gets better, the difficulty level and amount of techniques they face increases. The defender cannot hit the attacker, and the attackers are excused if they hit the defender.
Sorry MAC guys: I used a wimp32 only browser plugin
/Marcus