Where do you source your Spatial/GIS data layers from?gou

One of the most common things I see on GIS forums is an interest in acquiring spatial data for a specific project. This is especially true for new or ad hoc GIS uses, it is very daunting to build a GIS system from the groundup. I have also noticed that posts detailing free data sets tend to attract the most visitors.

I would like to hear your experiences in obtaining spatial data or base line data for your GIS system. Or if you have any issues obtaining data post them on the forum - perhaps someone can be of assistance. I will follow up this posting with some ideas on how to obtain data.

Also what new technologieshave you been using to obtain data.