A variable number of manipulates... I guess the answer depends on how you have structured your code. Do you want the number of manipulates to depends dynamically on some kind of value?
n = 6
Manipulate[Evaluate@Table[u[i], {i, 1, n}],
Evaluate[Sequence @@ Table[{u[i], 0, 1}, {i, 1, n}]]]
Evaluate is needed to ensure that the arguments will evaluate. Manipulate holds its arguments.
Sequence is needed to turn the list from Table into a sequence of statements.