In a pageblock table I want to render more than one records returned by statndardcontroller or extension controoler.

How can I specify the recordId or the record index in pageblock table?

e.g.

sr no.                   name                  age              city

1)                          tom                   22               boston

2)                           jim                       33              ny

3)                         shaun                     34               LA

I can retrieve name,aga and city.. but my controller can not get record index

i.e 1 for Tom

2 for Jim

3 for shaun etc.

Is there any way to render dynamically in visualforce?