Open Peeps - A hand-drawn illustration library.
Looka - Make a logo you’ll love with Looka Logo Maker.
Control Illustrations - 108 free flat illustrations with customizable characters
Logo Dust - Free logo designs for your projects, added every week
Craftwork - A collection of User Interface resources made by Craftwork
Canva Logo Maker - Create your own custom logos without having to hire a designer with Canva's impressively easy to use logo maker. Completely free, completely online.