Ring4 Meeting - Dead simple video conferencing - free, in browser
Retweet Picker - Retweet Picker is an online tool that is helping you to select the random winner from Twitter for the giveaways.
Stork.ai - AI-Based Collaboration for Hybrid Teams. Rich media messaging, advanced video and voice conferencing, auto-transcribing and screen sharing. Serendipitous meetings at the water-cooler with your human and AI teammates.
Twesocial - Twesocial helps you grow your twitter with real twitter followers. Real results, real people.
openmeet - Account free video conferencing with a rooms component that lets you use VC within a physical meeting room. The server can also be hosted in your own cloud for extra privacy/security.
Tweeteev - Get more Twitter followers with the best twitter growth service on the market. Tweeteev will effortlessly grow your twitter profile with real, active followers.