I use Moskol 100% DEET (its actually 95% DEET). Works pretty good.
DEET isn't a carcinogen in humans, and while it is slightly toxic (especially if ingested or inhaled, which you really shouldn't be doing, btw) it's safe if used infrequently.
As for West Nile Virus, its not 95% (that's huge); an estimated 20% of infected people will develop west nile fever (a flu-like condition) and only a small percentage of those (less than 1% of all people who contract West Nile Virus) will develop the really severe symptoms we hear about.
You always want to be on the lookout for dead birds and stuff, though; if you see a dead bird, it's a dead bird. If you see two, it's probably a coincidence. But if you come across three, you're probably safer assuming there's a potential problem.
Oh and for those mosquitos that sneak a bite in anyway, Tiger Balm works well at iliminating the sting, the itching and the "swelling" (the little lump the bite causes; I guess it's called swelling -- if you're really SWOLEN, in the traditional sense, you probably want to seek medical attention. Specially if you aren't certain what bit you.)