  We investigate the effects of gemini surfactants, telechelic chain and lipids
on the nature of micelles formed by conventional single-tail surfactants in
water by carrying out Monte Carlo simulations. In a mixture of gemini and
single-tail surfactants in water we find direct evidence of micelles of
predominantly single-tail surfactants some of which are dynamically
cross-linked by gemini surfactants when the concentrations of the geminis is
only a few mole percent and their spacers are {\it hydrophilic}. In contrast,
mixtures of lipids and single-tail surfactants in water form only isolated
micelles, each consisting of a mixture of both species, without cross-links.
