Some of the stuff that Sony makes are specifically for iPods. However, Sony does make stuff specifically for the Walkman, so you should try there first. The bottom connector thing is proprietary, so it might be difficult to find third party accessories that work with this connector rather than the headphone jack.
Here's a link to the SonyStyle online store. They're not cheap, but they should work.
http://www.sonystyle.com/webapp/wcs/stores/servlet/CategoryDisplay?catalogId=10551&storeId=10151&langId=-1&categoryId=8198552921644515824
hi folks!
looking for some help please, just bought myself an mp3 player for crimbo which is the 4gb sony walkman[NWZ-S616F]. while i am very happy with the player itself i would like to get a docking station for it, the problem is everything i see seems to be for ipods, i do no that sony have one but would like to no whether my player is compatable before i buy or if anyone knows of any other docking stations they would recommend for my player i would be most greatfull
Thankyou......

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic