"I guess I'll have to start the thread since it doesn't seem like anyone is gonna" edition
Before asking for a wallpaper, reverse image search it. This function is built into 4chan now. Its not hard to do.
Remember you'll get more rates if you rate others.

>Resources for Android, iPhone and Windows phone.
http://pastebin.com/JzWPVMGP - General Resources: fonts, wallpapers, color palettes
http://www.mediafire.com/view/bu0e8ordiw0il3y/banner_tutuorial.png - 'Quick and Dirty' Banner Tutorial

>Android Guides:
http://pastebin.com/G3Zde2ga - Basics and terminology to know for android.
http://pastebin.com/KHk9ZuLF - Read this after the basic/terms guide, and before your "first time post"
http://pastebin.com/86gCz85D - Starting place for a customized android notification bar. Outdated
http://pastebin.com/vuXnm1wi - WebMs made easy

>iPhone Guides: are these deprecated?
http://pastebin.com/qGHi8GRr - Crude iPhone ricing guide
http://pastebin.com/Zzj7aGzc - Jailbreak/theming guide
http://www.mediafire.com/?xptygbsj9eqos56 - Aiko Nation Theme.

>Windows Guides:
http://pastebin.com/nE6F3zVp - thals's /w/ Guide for Ricing&Hacking Windows Phone 7 and 8
http://i.imgur.com/znGGUeT.jpg - Infograph style guide