I am currently running the JoelDroid S2 version 2.1 ROM on my SGS2. It is pretty damn awesome to run features found on the Samsung Galaxy Note II especially Multi Window and Smart Stay.
I just flashed the new android 4.2 keyboard zip onto my SGS2. In my opinion it is the best keyboard / swipe keyboard available.
Download Source: pocketnow.com
There is a setting in ‘device options’ under the ‘screen’ tab to set the screen to ‘negative mode’. It looks freaking awesome.
I discovered Zedge recently when looking for a new ringtone for my SGS2. With Zedge I found a library of over 500000 ringtones from all walks of life (comedy, music, movie themes, TV themes, life, etc). They do alarm tones and individual ringtones for individual callers as well as notification tones. (sweet). The interface is simple and effective and one can preview, add to favorites, share, see uploader information and save tone in a number of ways.
They also do backgrounds, and have an awesome library of photos and images which are updated regularly. A brilliant, brilliant app. I highly recommemd Zedge. Link: Zedge
Backgrounds Box HD is a new cool wallpaper app which has more than 900,000 wonderful wallpapers and about 2,000 new wallpapers added everyday. You can always find what you want. You can even search wallpapers by color. I highly recommend you to install it.
Link: http://market.android.com/details?id=com.adao.gano.bbhd3