Store Manager for X-Cart recently got even better!
Version 1.5.18.495 includes several improvements and new features in product import/export as well as some minor changes
1. Export improvements - select fields you want to export specify custom captions and order of appearance
2. Import improvements - ability to specify more than one category for a product to be imported into, subcategories supported
3. Several minor improvements and bugfixes
http://www.xcart-manager.com/