Mosquito Force Field
Alaskans take their "cologne" very seriously. They have to -- if they leave home without bug spray during certain times of the year, it's very likely that they'll come home covered in mosquito bites.
Alaska boasts an impressive 30-plus species of mosquitoes. Although some don't snack on humans, the majority certainly do. This reduces people to a walking buffet for swarms of these unwelcome insects. DEET repellant is currently the most effective defense against mosquito attack.
All those chemicals can't be good for one's skin, though. A mobile force field that protects entirely against mosquitoes would surely be popular among everyone from the avid outdoorsy types to those who just want to walk to their mailboxes without being attacked.