Ruby on Rails Web 2.0 Style

Ruby on Rails Web 2.0 Ajax intensive website (With Sphinx searching gem) This Website is a specialised Classified Board with a social networking style profile pages to match. ? This bid is just for stage one which is a simple ability to: 1) Two different types of sub users (Posters and Searchers) to sign up and register with a username and password 2) Posers will have the ability to add classified adverts to the board and manage them (delete). The adverts will expire in a certain time. 3) The Searchers will beable to search specific location tags, and type of classified tags (preferably using the sphinx gem) on the classified adverts the posters add. Things like Most popular 10 adverts, Newest 10 adverts, Tag Clouds (using sphinx)? etc. would be implemented. The is all the funcality i would want to see for the first stage. Perhaps further future work for later stages I have ideas for. The design would be CSS based and a simple clean web 2.0 style.