Lastname, Firstname [or username or page name]. "First several words of the Facebook post..." Facebook, Day Month Year posted, time posted [if available], URL.
Penguin, Oscar. "Root beer floats are in honor of National Library Week..." Facebook, 18 Apr 2013, facebook.com/openguin/posts/10154065808067067.
Username. "First several words of Tumblr post (if any, otherwise omit)..." Title of Tumblr blog, Day Month Year posted, time posted (if available), URL.
libechillbro. "Root beer floats are in honor of National Library Week..." Oscr, 18 Apr 2013, 1:28 PM, libechillbro.tumblr.com/post/125058827619/root-beer-floats-are-in-honor-of-national-library-week.
Lastname, Firstname [or single username] (handle). "Full text of tweet." Twitter, Day Month Year posted, Time AM/PM, URL.
Penguin, Oscar (@libechillbro). "Root beer floats are in honor of National Library Week, and we'll be handing them out from 2:30-4:30 this afternoon." Twitter, 18 Apr 2013, 1:28 AM, twitter.com/libechillbro/status/2651151366.
Lastname, Firstname [or single username]. "Title of YouTube Video." Publishing Website, Day Month Year posted, URL.
Penguin, Oscar. "Root Beer Floats." YouTube, 18 Apr 2013, www.youtube.com/watch?v=4ICGujpcO28.
Lastname, Firstname [or single username]. (handle). "First several words of Instagram post (if any)..." Instagram, Day Month Year posted, URL.
libechillbro. "Root beer floats are in honor of National Library Week…" Instagram, 18 Apr 2013, instagram.com/p/5pjGjvjTH6
Lastname, Firstname [or single username]. "Title of audio track." Publishing Website, Day Month Year posted, URL.
Penguin, Oscar. "Root Beer Floats" SoundCloud, 18 Apr 2013 www.soundcloud.com/oscarthepenguin/root-beer-floats.
This is a practice tool, not a citation generator.