I go to ManageFeatures.aspx and I see bunch of features that don't belong there and they are not in the 14 hive's feature folders. I go to the backend database and look in alldocs, features, and featuretracking tables and don't see them. Now, where do they came from and how do I get rid of them?
You could use PowerShell to get the GUIDs of the features you want to get rid of, here's a blog form Glyn Clough on how to do this: http://www.glynblogs.com/2010/08/powershell-commands-to-list-sharepoint-features.html
stsadm -o uninstallfeature -id <feature_guid> to uninstall the feature (might be able to do the same with PowerShell, I think).