I posted earlier in the year about some of my favourites.
As part of our Autodesk subscription service, we actually have access to some very useful extension tools. Log in to the subscription Centre. Under downloads, you will see 'Product Enhancements'. This will take you to a list of extensions.
Rather than re-typing it, here is a link to the Cadline Community with a blog outlining available extensions.
My recommendation is the Revit 2015 extension package which provides tools for bulk uploading of shared parameters into families. I have mentioned E-transmit in the past too if you spend time before issuing models, purging and deleting views / sheets.
So take a look at your subscription centre if you haven't already, we pay enough for it!!