Hate the amount of wasted space on the Lync Contact List. The way I have my window set up, there's potential for a good 60% reduction in the window size.
I really prefer the clean / minimalist approach so I turn off all photos from the contact window.
I don't need any of the "Groups / Status / Relationships / New" tabs, the "Conversations / Calendar" tabs, the always existent "Other Contacts" folder, seeing myself / my status / my location, etc.
Same thing goes for the Instant Message / Conversation Window. I just want to see a person's name, messages sent, messages received (just like today's iPhone Messages app). I don't need or want anything more and everything else just seems to be a waste of space and could be all condensed into a tiny icon which opens up "Other Settings" or "Other Options"
The idea that comes to mind for the most minimalist design layout comes from iPhone Messages app or even old AIM buddylist windows.