Social challenge: Readdle started a social challenge with the promise of making Printer Pro for iPhone free of charge if Readdle’s Facebook page hits 10’000 likes. 

Via M4tt.

Emotional design/giveaway: Mailchimp is giving away hats for cats (the giveaway is just about over right now). Here’s the video that the page linked to.

Emphasis: underline a fact at the right place. 

Freebie: Hipmunk (@thehipmunk) is giving away a bonus level for Angry Birds. Merry Christmas everyone.

Give aways (produce things that people love): Mailchimp (@mailchimp) is giving away a coloring book for children with its logo chimp as the main persona. 

Choice: Zootool (@zootool) offers a pro account and leaves you a choice for how much you want to pay. The range is from 1$ to 100$. Check out the landing page and the email campaign that are very skillfully crafted.

When you move it to the left (which will be a lot of people’s first reflex I’d argue): the grass in the illustration grows thinner and at 4$ says: “We won’t be able to feed the Rhino anymore, but that’s ok!”

Below the whole payment arrangement, you’ll see the Here’s what you get details.