[Sony Ericsson Xperia Neo, Pro] shardul_seth:
A one-stop no-pain solution for enabling and using USB OTG mass storage on your android phone!

What is USB OTG?

It stands for USB On-the-Go!

"It is a specification that allows USB devices such as digital audio players or mobile phones to act as a host allowing a USB flash drive, mouse, or keyboard to be attached." - Wikipedia

The stock kernel allows Mouse & Keyboard, but USB storage is missing..

Features:

Stock and custom kernels supported

Mount and Unmount drive with a single click

No Ads!

Full NTFS support built-in!! (from v3.0.3)

Automatically start on device connect (intent broadcast) (from v3.0.3)

Notification when drives mounted! (from v3.0.3)

One click access to unmount (from v3.0.3)

Option to enable UTF-8 if kernel support (from v4)

Automatically open explorer after drive mounted (from v3.0.7)

One click debugging and feedback (in app) [Donate version only]

What phones are supported?

Sony Ericsson Xperia Neo, Neo V, Ray, Arc and the Arc S! Modules for stock kernel on second post.

If you get it to work on other devices, please PM me and I will add them to the list.

Please note that this app is an "Helper" app.. it will not magically make your kernel support USB Mass storage ;)

What are the requirements?

root (su binary)

busybox

USB OTG cable

How to use on stock kernel?

See this post to load modules!

WARNING

I will not be held responsible for any damage to your device. Do not use for a long time, u may risk burning the device chip/motherboard due to the voltage supply in host mode.

Screenshots and Screencast:

[YOUTUBE]uFN0ftVxk0o[/YOUTUBE]

Download: USB OTG Helper

For modules for stock ROM / other ROMS -> See here.

Changelog:

v5 (2012-10-27):

+ Option to select system busybox or in-app busybox (fixes a lot of bugs in newer devices)

= Updated internal busybox binary

= Bumped version number :)

v4.3.3 (2012-10-26):

+ App log also saved in debug info [debugging data is much more meaningful now]

+ Settings to enable/disable debugging mode [off by default]

v4.2 (2012-10-24):

+ Supports multiple drives via powered hub [sda to sdz block devices]

= (Fix) Folder open intent (still needs OI or ScriptManager)

v4.1.5 (2012-10-20):

= (Fix) umask error (some users could not mount ext2 and ext3 drives)

= (Fix) folder open intent (but works only with some apps eg., OI file manager or Script Manager)

= minor bugfixes

v4.0.0 (2012-07-29):

+ Lots of visual changes

+ Settings (Preferences) activity

+ Changes for ICS (Action bar)

= (Fix) Choice of file explorer to open the mounted drive

= (Fix) Notification is cleared on Unmount

= Code optimizations

- UTF-8 mode off by default (enable in Settings menu)

v3.0.7 (2012-07-04):

+ UTF-8 default if kernel supports nls_utf8

+ Automatically start file explorer after mount

v3 (2012-06-27):

+ Full NTFS support (with write support)!

+ Automatically start app on device connect (intent broadcast)

+ Notification when drives mounted!

+ One click access to unmount

- Removed setup (to support many more devices)

+ Lots of optimization and bug-fixes!

v2 (2012-06-19):

+ NTFS module integrated

+ Bugfixes

+ Now NTFS drive can be explored with ANY file explorer (Fixed bug)

Touble-shooting!:

1. Settings -> "In-app Busybox preferred" -> Uncheck. Then try again.

If still not working:

1. Settings -> Debugging mode -> Check.

2. Do the steps that fail.

3. Send me debugging data (in the app itself) ;)

Credits:

DooMLoRD @xda-developers.com - For the original idea and implementation.

shardul_seth @xda-developers.com - For creating this app.

Bug reports, feedback and constructive criticism , please send a PM ;)

Please do not download from below attachments. They are for historical reasons only.