Many bloggers embed the Feedburner chicklet onto their blog to show how many readers they have. Unfortunately, this number is far from perfect. People may have subscribed to your feed from multiple RSS readers so there could easily be duplicate counts for the same user. This is especially true for blogs that have been around a while as people have changed rss readers over the years. There are also ways to fake the Feedburner subscriber count. The video below from The Next Web shows a way to do this using NetVibes.
The best real way to inflate your subscribe count is to get your feed offered by an RSS Reader in one of the recommended bundles - but that's much easier said than done.