I've got that cheat sheet saved on my computer and I've looked at it several times before, but today was the first time I realized that you can hit '&' to repeat the last :s command on the current line. Very slick!!

Yep, and 'g&' is really helpful. It runs the last substitute across the entire file, preserving flags.

I thought I was a Vim master and I just looked at that and discovered once again how stupid and inefficient I've been this whole time. This sort of thing keeps happening to me with Vim.

Source: http://www.viemu.com/a_vi_vim_graphical_cheat_sheet_tutorial...

That's the tutorial that fed me that chart in easy-to-manage pieces, easing me into vim nicely.

Also highly recommended, the rant by the same guy: http://www.viemu.com/a-why-vi-vim.html