From: Rohit Dasari

  There's this consonant in Tamil (someone called it a retroflex
lateral fricative or something--excuse my ignorance when it comes to
technical terms) which sounds uncannily like, but isn't quite, the
American r (the MID-WESTERN American r: from what I've been reading
about the rhotic <is that what it's called?>). It's transliterated in
English as [zh]--you can find it in the Malayalam name for Cochin:
Kozhikode. It's listed in the same row in the Sanskrit-like Tamil
alphabet table as the other glides/fricatives/whatever:

            ([j], [r], [R], [l], [zh], [v])

Piotr will probably slap my hands when he gets back, but you might try this link:

http://www.unil.ch/ling/phonetique/api32-eng.html#symb_retroflex_s

 

If you are set up for UTF-8 (Unicode), here they are:

[ ʂ ]     [ ʐ ]   

The first is S with hook, then z with retroflex hook. An American R? That would be the upside down little R,  [ɹ], unless you are thinking of the rhotic schwa, as in 'father', [ɚ] ... My R's don't sound at all like the hooked s or z.