I am a big fan of e621, but I also scoot around on rule34.paheal.net for my non-furry needs. That site is overall pretty awful with its bugs and lags and avalanche of ads, but they have something I would like to see implemented here.
On the side of the page, the first dozen words of the last dozen comments are displayed with a link to the commented-upon image. This attracts more people who are curious about or interested in whatever the random bit of text they see is.
This means more comments, which means more views. This means when a person stumbles across a wonderful image that's buried back in the archives and comment on it, it gets a chance for new people to spot that comment and jump over to the image and give that image (and artist and character and fetish) a second chance at exposure.
It's much more user-friendly than the Comments page, as it's a cute little corner-of-the-eye thing. I think it would increase traffic here considerably if implemented.
Updated