Here is a free (GPL) product data export script for AspDotNetStorefront. The script is open-source and written in VB.Net.
Free CSV Product Data Exporter for AspDotNetStorefront
To install it, all you do is copy the scripts to your website. You can specify a password to password-protect the data export. The exported data is formatted as Excel-compatible, CSV (comma-separated value). This script is specially designed for high-performance and low-memory usage, and it will compress output to save bandwidth.
After installing, open the page and then you can enter the password and click Export. The raw data will start displaying in your web browser, and you can then save this to your computer. You can copy the URL and use it where needed to dynamically get your latest product data at any time. You can use this as source data for an Excel template that generates data feeds to Google, Bing, etc.
This script exports the first category and manufacturer for each product. It also uses a refined set of filters to exclude products that should not be listed in search engines. The code is very well documented, so you are free to read through it.
Any feedback would be appreciated.