Sipdroid - Free and open-source SIP/VoIP Client
Uber - Uber is a website and mobile app that allows you to get a ride similar to a taxi service from your phone.
Zoiper - Cross-platform VoIP softphone dialer for SIP and IAX systems
Lyft - Lyft is a mobile app that lets you get rides from pace to place for a fee. If you want to be a Lyft driver, you can go to their website and easily sign up to start driving for them. Read more about Lyft.
MicroSIP - MicroSIP is a free portable SIP softphone for Windows based on PJSIP stack.
BlaBlaCar - BlaBlaCar is a ride sharing service that connects travelers throughout Europe.