A wide family of methods is described for sampling in the canonical ensemble. The Bulgac-Kusnezov method is generalized to include a more complicated coupling structure and stochastic perturbations. It is shown that a controlled fluctuation of the potential surface or force field in a molecular model may be used as part of a sampling method (instead of the more standard friction or driving term). Numerical experiments demonstrate that the family includes methods that are effective for recovering canonical averages.