Google Spreadsheets doesn't have AutoFilter yet, but a Google intern built one using the API. You can view your own spreadsheets, but you must make them public before.
Besides restricting the rows to the ones that contain specific values, you can create custom filters by defining your own boolean expressions. It even works with natural language expressions like "value is 5 or value is greater than 10" or regular expressions like 12/*/2007 (any date from December 2007).
"The API gave me access to practically all my spreadsheet data, so I had the flexibility to do whatever I had in mind. Within a few hours, I had a pretty powerful little application that could filter using easy dropdowns on each column. But I wasn't done -- I wanted more control over filtering. I added an expression parser that understands fuzzy filters -- things like contains North or New -- just as well as it understands more precise (but intimidating) traditional expressions," explains Alex Komoroske, the author of the app.