Web Page Preview on Tabs:
Its faster to click on it than to wait for the preview to appear
Torrent Downloading:
I honestly prefer a full program for that, uTorrent
Opera Mail:
Gmail is better, and I prefer using the full gmail, not a program that downloads the emails, or syncs them
A Built-in RSS Reader:
Could be ok, I still prefer Google Reader online
Opera Notes:
I like to have my notes synced everywhere, if i can view them on my phone it could actually be good.
Mouse gestures:
Firefox has that (with an extension), I tried it but never liked it. I tend to play with my mouse all the time, and triggered gestures by mistake
Reload page every x minutes:
Most apps now have an auto refresh like Facebook or Twitter. And honestly F5 is really easy to do. Also there is a firefox and a chrome extension to do this
Clone Tab:
For the twice in a year where I might need this function, it takes 1 second to do this manually