An homage to Dinosaur Comics would be kinda redundant, since its whole format is to graphically copy itself every time. When Ryan North lets others do guest comics, the artists inevitably restyle it.

Other comics I'd like to see homaged (is that a word?) that may be more generally known (regretfully) than Pictures for Sad Children or Cat and Girl:

Sinfest (go manga!)
Diesel Sweeties (go 8-bit!)
Wondermark (go victorian clipart!)
Schlock Mercenary (badly drawn sci-fi!)
Sheldon (pop culture references and talking duck!)
Questionable Content (hipster sitcom!)
Laugh-Out-Loud Cats (pop culture references and hobos!)
Axe Cop (sub-juvenile murder fantasies and no plot!)
Something Positive (self-referencial cynical dark humor!)
but NOT xkcd (if you feel the need for stick figures, go with the joyfully tacky Chainsawsuit or Cyanide & Happiness... or mash them all together)

Or you could do the web (and especially me) a favor and make an ending for Goats' multi-universe story since Jon Rosenberg doesn't really want to.

As a dedicated webcomics maven I am available to contribute story and gag ideas (but can't draw worth shit, evidence here)

I'd have a perverse desire to do all the obviously digital ones (like Diesel Sweeties) as pencil work, but keeping the look, like doing DS on grid paper.

Speakofthedevil, MeFi's Own Lore just did a Guest Dinosaur Comic, or rather, an "Animals That Went Extinct More Recently Comic"