I presume we're not including people we actually know. I'll also skip fictional characters such as Jessica Rabbit. So, celebrities, then.

Shakira - mostly to see what she'd be like in bed (or elsewhere)
(SPOILER)

Kate Middleton - mostly to say I've shagged the queen (eventually)
(SPOILER)

Una Healy - It's rare that I get caught up in someone's eyes, but I always do with her.
(SPOILER)

Karen Gillan - you have to watch Doctor Who to really understand this
(SPOILER)

Diora Baird - Damn. Damn, damn, damn.
(SPOILER)


Juuuust missed out: Hayden Panettiere, Jennifer Ellison (would top my list pre-pregnancy), Miley Cyrus, Jennifer Metcalfe, Mariah Carey, Pixie Lott, Sofia Vergara, Emily Atack and Emma Stone.

If I could pick them at whatever time I considered them to be a their prime, it would be:
Mariah Carey (SPOILER)

Jennifer Ellison (SPOILER)

Rachel Stevens (SPOILER)

Diora Baird (SPOILER)

Heidi Klum (SPOILER)