Finally took the plunge and flashed CM9 the other day. So smooth and enjoyable to use, with so many potential customisations make it a pretty perfect ROM.
It sounds silly, but my favourite part about the ROM is the status bar...that stock Galaxy Nexus look/size. Samsung, why did you have to make the S2 (even the S3) status bar a few pixels bigger? It seems pointless, and looks less slick.
Wall - Source is unknown I'm afraid. A Tineye or reverse Google image search might get you a result
Clock - BobClockD3 (Play Store)
Icons - Sanscons
Launcher - Apex (Play Store) surprisingly... Trebuchet is great, smooth and stable, but needs to implement the ability to change app icons for us customisers!