The present invention generally relates to microfluidics and, in particular, to systems and methods of producing droplets (55), including double and other multiple emulsion droplets (55). In some embodiments, the present invention is generally directed to systems and methods for producing multiple emulsion droplets (55). In some cases, the multiple emulsion droplets (55) may have relatively thin shells. These may be produced, for example, in a one-step process where multiple fluids (15,25,45) are brought together at a junction (18,48), or by passing the multiple emulsion droplets (55) through constrictions (76) in microfluidic channels. Other aspects of the invention are generally directed to systems and methods for using such double and other multiple emulsion droplets (55), kits involving such double and other multiple emulsion droplets (55), or the like.