This mini-rant came on the heels of an interesting twitter discussion: https://twitter.com/kennwhite/status/591074055018582016
Provider / "Secret" Key
GoldenFrog / thisisourkey  
GFwVPN / gfwvpn  
VPNReactor / VPNReactor  
UnblockVPN / xunblock4me  
IBVPN / ibVPNsharedPSK!  
Astril / way2stars  
PureVPN / 12345678  
PrivateInternetAccess / mysafety  
TorGuard / torguard  
IPVanish / ipvanish  
Moral of the story: Don't believe everything you read, on say, TorrentFreak and PCMagazine. And (crucially) think about your threat model—are you guarding against amateur WiFi snoops at Starbucks or Marriott? Reducing identity monetization profiling by ISPs (ie ad tracking)? Minimizing exposure to government surveillance? Trying to be anonymous online? If the latter, a VPN won't help much.
Citations:
https://www.google.com/#q=goldenfrog+thisisourkey
http://www.gfwvpn.com/?q=node/224
https://www.vpnreactor.com/android_l2tp_ipsec.html
http://unblockvpn.com/support/how-to-set-up-l2tp-on-the-android.html
http://www.ibvpn.com/billing/knowledgebase/34/Set-up-the-VPN-connection-on-Android-handsets.html
https://www.astrill.com/knowledge-base/50/L2TP-IPSec-PSK---How-to-configure-L2TP-IPSec-on-Android.html
http://billing.purevpn.com/knowledgebase.php?action=displayarticle&id=33
https://www.privateinternetaccess.com/pages/client-support/
http://torguard.net/knowledgebase.php?action=displayarticle&id=58
https://www.ipvanish.com/visualguides/L2TP/Android/
@PacketSmuggler: Well, despite I have nothing against Cryptostorm. They can still "log" you: you are still connecting to their servers with your IP address and your traffic is still routed through their servers.