I have been using most of these for a while now – like Gruber I too do not have Flash installed on my Mac (with exception of Chrome) so some of these extensions are vital:

• Shaun Inman’s HTML5 Audio Extension – helps to alleviate your from Flash audio players.
• Sessions by David Yoo – a great way to save your current Safari state, especially when you want to restart your machine without losing your place.
• YouTube Wide by Pedrocc – makes those YouTube videos bigger, even if you don’t have flash.
• Breaking News by The New York Times – this cane be annoying as it drops down a bar along the top, but I found that I really like it 90% of the time. Most of my complaints come from what they deem ‘breaking news’.
• Vimeo Wide by Potatofactory – like YouTube wide, but for Vimeo.
• Keming by Jim Ray – make things more readable.
• View Style Sheets by Soner Eker – ever wonder how that element was styled, I do all the time.
• Javascript Blacklist by Drew Thaler – a great extension to block things like Tynt and Snap, keeping your veiwing experience nice. Especially helpful if you copy text to quote people, so that you don’t get the ‘Read More: http://…’ crap
• YouTube5 by Conor McKay – this is the best plugin, it forces YouTube, Vimeo and Facebook to play HTML5 versions of the video – this is a must have if you like battery life and keeping your Mac cool (temperature wise that is).

Now get to installing.