FeatureServer is an implementation of a RESTful Geographic Feature Service. (What is REST?) Using standard HTTP methods, you can fetch a representation of a feature or a collection of features, add new data to the service, or delete data from the service. Use it as an aggregator -- post your GeoRSS feeds to it, and then browse them using WFS. Use it as a translator: use the OGR DataSource to load a shapefile and open it in Google Earth. Use it in any way you like.

Use NADCON (North American Datum Conversion) to convert latitude and longitude from NAD 27 to NAD 83 or from NAD 83 to NAD 27.