Read somewhere a while back that mosquitos serve absolutely no purpose in the overall food chain. The insects/lizards/birds/whatever that hunt and eat them have enough other food sources that if mosquitos disappeared altogether it wouldn't have any negative consequences for the overall ecosystem at all. They're like the small pox of the insect world. Eradicate them entirely and they wouldn't be missed in the slightest.
Citronella works - for maybe half an hour, tops. Haven't tried Skin So Soft.