We don't have many guidelines, other than that it needs to work on a business card and convey some level of professionalism, but not be boring.
Design is an important aspect of what we deliver to our partners so our image should convey that we are creative.
While we focus on mobile, We do NOT want any designs that have phones in them.
Logo must work in black and white, so please provide both color and black / white versions when submitting.
Looking for something that features an illustrated mark, with well defined lines.
Trying to stay away from logos that look like 3D renderings and clip art.
Go forth and be creative.