What are some "mainstream" lightweight alternatives to storing files in .csv format? [duplicate]

Question

I'm on a project which heavily favors the use of .csv files for data storage. I see many issues with using .csv, especially for storing relational data. Parsing .csv is generally a pain, particularly when using ad-hoc column assigments.

I've advocated the use of XML and minimal databases such as SQLite, but I'm looking for "faster, better, cheaper" alternatives.

What are some other, "mainstream" lightweight alternatives to .csv files?

Also, what about CouchDB. How does it compare to SQLite in terms of lightweight-ness?

EDIT: I missed it. This question has been asked before.