I recently came across Google Refine (now OpenRefine) – it’s not a service for validating CSV files, it’s a tool you download locally, but it does provide a lot of tools for working with data and detecting anomalies.
As mentioned in a reply, “CSV” has become an ill-defined term, principally because people don’t follow the One True Way when using delimiter separated data
http://www.catb.org/~esr/writings/taoup/html/ch05s02.html
EDIT/UPDATE (2016-08-09):
CSV Currently Becoming a Well-Defined Term by the W3C CSV Working Group