The closest thing I know of for sewing is PatternReview.com which has lots of reviews of sewing patterns - excellent coverage of commercial dressmaking patterns such as Vogue, Butterick, Simplicity, New Look etc plus loads of less well-known companies. Not sure about other types of sewing project as I mainly sew clothes - there are certainly some, but I don't know how good the coverage is. It also has tips and runs contests. It doesn't really have the organising your stash and projects aspects in the same way that Ravelry does, but it has forums (fora?!) and tips sections, book reviews and runs competitions as well.
I think you can access reviews in the last 6 months without registering, and then a basic membership is free, but allows you full access (at the cost of your email address, of course). There are also paying membership options as well.
It's well worth a browse for the pattern reviews - I nearly always have a look to see what others have made of a pattern before buying/starting - sometimes people will highlight mistakes or confusing parts of the pattern and suggest better ways of doing things!
What Ravelry-like aspects are you looking for - the organisation, the project ideas or the seeing what other people are doing?
i do keep considering making a site like ravelry but just for sewing. its just the time involved if it takes off thats the worry. oh i do mean a completetly interactive site. just having a chat to another of my developer friends now.........................