First we have the Doctor and Rose(from the tv-show Doctor Who), as seen in issue 6 when they appear as passers-by on a London street.
Link to Rose
Link to the Doctor
And the some Tara and Willow love, as seen in the episode Real Me(Buffy, Season 5). Link.
Finally, Buffy from Fool For Love(Buffy, Season 5). Ouch. Link.