Skype and YouTube for me.

The browser.

If you're talking about making channels on YouTube mobile, then I'm afraid I can't help you there, since I use YouTube solely for watching vids and listening to music.

As for Skype, it's just what my friends use. I don't even know what oovoo is, lol.

Chess is the main one for me

Manga Rock, Chrome, Youtube, Facebook and Messenger

I have a 3G Vita that I have been using as my phone for the last 6 months. Here is a list of apps I have been using.

Skype - For phone calls
Twitter
Facebook
Built in E-mail App
Built in Calander App
Crackle
MLB.TV
Tunein
Hulu
Netflix
Snagfilms
Solacal - scientific calculator
Sola Weather
Notepad DX
Spirit Level - Leveling Tool
Web Browser
Photo Viewer/Camera
Video Player and PlayStation Video
Music Player
Paint Park Plus - Photo Editor and Drawing App
Wake Up Club - Alarm Clock

Along with that, I also use a lot of mobile web sites for everythng from banking to word processing, spreadsheets, shopping, etc.

By far the best Mobile device I have ever owned. Cheaper, more fun, and just as versitile as android or ios. It's an absolute shame more people never gave it a shot.

*Note - Some of these may be iOS only.*

Elevate
Tip Calculator
Instagram
Playstation App
Vine
CamScanner
Fitness Buddy
iFitness
SparkPeople
Amazon
Wikipedia
Translate
Dictionary
Audible
Amazon Prime
Pandora
Convertbot
Pic Stitch
Twitch
Google Earth
Bitmoji
iTranslate
RepairPal
U.S. Constitution

I just use it as a MP3 player and to surf the net once in a while.

Vaulty: keeps my private pics private
Sound Hound: if a song is on and i want the lyrics, it listens and gives me the info
Google Goggles : take a pic and it googles the image

I have an Android. Here are some good apps that I have and use quite a bit:

Zedge: Tons and tons of user uploaded wallpapers, ringtones, notification sounds, games etc. You will find lots of good content; all for free.

Songza: Music playlists that are curated for you based on questions you answer (ex: are you at the gym? Quiet evening? etc). Free.

CCleaner: A handy tool that frees RAM space as well as storage by deleting unneeded cache, message logs, and other stuff. Free.

Snapchat: Free pic/vid messaging app. You can send snaps (pictures or videos that are visible for max 10 sec once opened) to your Snapchat contacts as well as adding stories that can be seen for 24hr. Very neat app to have.

Pushbullet: (paired with Chrome extension on PC): gives me the ability to view notifications on my PC, send files back and forth easily, and even text from my laptop. Free.

Tasker: Pretty much a brilliant app that uses "if this then do that" rules that you customize. For example, if on home wifi, disable lock screen. If headphones plugged in, launch music. If between (insert times), silence notifications. IFFT (if this then that) is another app that uses this principle, except it is free. Tasker is $3.99.

McTube: Plays YouTube even when the screen is locked.

Twilight: Filters blue screen light to make night browsing easier on the eyes.

My Fitness App: Pretty self explanatory. Does almost anything your fitness heart desires.

Wakie: A social alarm clock that wakes you up by phone call from some random person from anyone (who has the app) around the globe. You can also phone people to wake them up. Some of the calls and responses you will get are priceless.

Hope this helped!