Allow full branding of ADFS login page, not just an image/title
Please provide more details on the kind of customization you would like to achieve with the ADFS sign-in page as well as the version of ADFS you are using.
Robin Gorris commented
Allowing customization in the same way you allow customization on the Azure Active Directory B2C preview would be a great improvement. http://blogs.technet.com/b/ad/archive/2015/09/09/azure-ad-b2c-and-b2b-are-now-in-public-preview.aspx
I want to provide html and css.
Omer Cansizoglu commented
Some customization ideas that will be needed:
1- Background color
2- Message section below the login section to alert/announce something such as maintenance to your own system.