Creddon - Tweet for a cause and a sponsor will donate $1 to charity
Mailjoy - Delightfully easy direct mail marketing. A DIY direct mail tool created for marketing and growth teams. Design, mail & track personalized direct mail postcards and letters. Digital marketers use Mailjoy to send data-driven mail campaigns.
Send Mail Get Mail - A postcard-sending website.
Momentum - Agile goal and performance management
Postacard - Text a photo to send it as a postcard for $3.
RealMailers - Send geo-targeted direct mail to 110M+ homes in the US