Question of the week, asked by more than one reader: "How hot is the kiss between Jim Carrey and Ewan McGregor in I Love You, Philip Morris? Although not tepid, it is not as red-hot as the kiss between McGregor and Jonathan Rhys-Meyers in The Velvet Goldmine (1998). Although saucy, not so much as that marinara-splashed buss between Spaniel and mutt in Lady and the Tramp (1955).

What is the mother of all puckers? What makes a great movie kiss? If it's surprising, furtive, transgressive or Hitchcocky.

Surprising: Spider-Man (2002), when title figure Tobey Maguire slithers headfirst down a wall to give girlfriend Kirsten Dunst an upside-down kiss. (If memory serves, Tony Curtis does something like this in Trapeze[1956] hanging from his feet, swinging to meet the mouth of Gina Lollobrigida in mid-air.)

Furtive: Atonement (2007), when James McAvoy pins Keira Knightley against the library shelves, thinking nobody is watching. (Likewise Mississippi Masala [1992], when Denzel Washington and Sarita Choudhury sneak off to Biloxi so they can meet far away from her disapproving family. Or A Place in the Sun [1950], when Montgomery Clift and Elizabeth Taylor kiss on the patio, where the partygoers inside can't see them.)

Trangressive: The Hunger (1983), when vampire Catherine Deneuve seduces medical researcher Susan Sarandon. (Likewise Twilight [2008], when vampire Robert Pattinson kisses, but does not bite, Kristen Stewart. Or when the leonine Beast Jean Marais first kisses Beauty Josette Day in Jean Cocteau's La Belle et La Bete [1946]. Or Brokeback Mountain [2005], when Jake Gyllenhaal kisses Heath Ledger away from the prying eyes of the city.)

Hitchcocky: Alfred Hitchcock was both master of suspense and master of the liplock, as seen in Notorious (1945), when Cary Grant and Ingrid Bergman go at each other hungrily, and Rear Window (1954) when Princess Charming Grace Kelly awakens her Sleeping Beauty Jimmy Stewart.

Other movie kisses to build a dream on are Jimmy Stewart springing a kiss on Donna Reed while she's on the phone in It's a Wonderful Life (1946), Nic Cage kissing Cher (who is engaged to his brother) in Moonstruck (1987), John Wayne subduing reluctant Maureen O'Hara in The Quiet Man  (1952), Gregory Peck and Audrey Hepburn sharing their first -- and last -- kiss in Roman Holiday (1953), Simon Baker overcoming Sanaa Lathan's resistance in  Something New (2006), Lauren Bacall planting a wet one on Humphrey Bogart in To Have and Have Not (1944), Drew Barrymore practicing her wedding smooch on good pal Adam Sandler in The Wedding Singer (1998) and Mel Gibson and Sigourney Weaver devouring each other's lips in The Year of Living Dangerously (1983).

Your five favorite kisses?