Well, I think we need a topic for the more uncommon/minor characters that appear for an episode (or more) like Ace London, Covington, Buffy & Muffy, etc.
I've noticed both Buffy & Muffy are a sort of recurring couple you see throughout the series.

1. Mach One for the Gipper (Buffy and I think Muffy possibly appears)
2. Louie's Last Stand (Buffy)
3. A Touch of Glass (as actual characters)
4. My Fair Baloo (Muffy)
5. My Fair Baloo (Buffy & Muffy)
6. A Star Is Torn (Buffy & Muffy)
7. Plunder & Lightning (Buffy)
8. Plunder & Lightning (Muffy)
9. The Golden Sprocket of Friendship (Buffy & Muffy)
10. Last Horizons (Buffy & Muffy)
11. Last Horizons (Buffy & Muffy a second time)
12. Vowel Play (Buffy & Muffy)
Also notice Fred (the rhinoceros guy) who appeared in A Touch of Glass appears in panels 1, 2, 6, 9, 10 and 11. There's plenty more who make an appearance but you get the idea. I like how the creators were consistent in making some of the same characters appear throughout the series. Anyway, I thought it was an interesting idea.