So, if you want to see naked women in movies, there are lots to choose
from. If you want to see naked men, there aren't many. I know the
rules on what is and is not permissible but still. The Piano (a bit
random, but fine), American Gigolo (wow, 2 seconds), Troy (the most
amount of naked male flesh I can remember). Mostly it's overhyped
2-second slots like Will Smith in I Robot (I haven't seen the movie,
so I am repeating what someone said to me, but I cannot call myself a
21st century citizen if my opinions are not regurgitations of what
other people tell me).

So my question is: give me 10 movies (if there even are 10) which show
a decent amount of naked male flesh, to a similar level as there are
naked women in Monster's Ball, Helen of Troy, The Swimming Pool,
Malena, Sex and Lucia, whatever.

And I mean decent movies, that were in the cinema or some such thing,
not porn, not straight-to-video, not made-for-TV.

I've gathered some material that I hope you'll find interesting.

"Movie Buff Checklist: A History of Male Nudity in the Movies," by
Marvin Jones, is an excellent reference source for film fans and
admirers of the male body:
 
Amazon: Movie Buff Checklist
http://www.amazon.com/exec/obidos/tg/detail/-/1888211040
http://www.amazon.com/exec/obidos/tg/detail/-/096237251X

Here is an entertaining essay from the Movie Buff Checklist that names
quite a few films containing male nudity:

A Little Peek: Male Nudity in the Movies
http://www.bjornsmestad.com/rwav/little_peek.html

An interesting article on the subject:

CNN: New film challenges full-frontal taboo
http://www.cnn.com/2004/SHOWBIZ/Movies/02/16/film.full.frontal.ap/

Nude actor databases:

Celebrity Nudity Database
http://www.cndb.com/browse.html?type=actor

Nude Actor Movie Database
http://www.wwmen.com/horseyncm/index.html

In the "Comments" section, rabaga-ga has mentioned "Women in Love," a
1969 Ken Russell film. The nude wrestling scene in this movie is a
stunner: sensual, beautiful, and filled with emotional power. The fine
British actors Alan Bates and Oliver Reed were at the peak of their
form in every way. To me, this scene stands alone as the most
memorable male nude scene of all time, and it may never be surpassed.

I have compiled a list of my ten favorite films that feature scenes of
male nudity. This is a highly subjective matter, of course. Your
mileage may vary. In most of these movies, the male nudity is rather
brief, but I value quality over quantity.

1.  "Women in Love" (Alan Bates, Oliver Reed)
http://imdb.com/title/tt0066579/

2.  "Don't Look Now" (Donald Sutherland)
http://imdb.com/title/tt0069995/

3.  "The Piano" (Harvey Keitel)
http://imdb.com/title/tt0107822/
 
4.  "Prospero's Books (Everybody is nude, including John Gielgud)
http://imdb.com/title/tt0102722/

5.  "Saturn 3" (Kirk Douglas)
http://imdb.com/title/tt0079285/

6.  "At Play in the Fields of the Lord" (Tom Berenger)
http://imdb.com/title/tt0101373/

7.  "Rapa Nui" (Jason Scott Lee, Esai Morales)
http://imdb.com/title/tt0110944/

8.  "Young Adam" (Ewan McGregor)
http://imdb.com/title/tt0289635/

9.  "Any Given Sunday" (Several actors in a locker room scene)
http://imdb.com/title/tt0146838/

10. "Starship Troopers" (Several actors in a shower scene)
http://imdb.com/title/tt0120201/

I hope this is helpful. Thanks for a most enjoyable question!

Best,
Pink

There is a lenghty scene in the film adaptation of "Women in Love" by
DH Lawrence where Oliver Reed and Allan Bates wrestle naked in front
of a roaring fire (film directed by Ken Russell).

The movie "A Room With A View" has a scene where several men (3 or 4,
I can't remember exactly) swim naked in a pool in the woods. The scene
lasts several minutes and shows them chasing each other, generally
mucking about etc.

In the original " Godfather" I believe there was quite a good view of
Marlon Brando's bare behind :) ( Back then it was still considered a
cute *asset* )

There's a book called The Bare Facts Video Guide that lists all
instances of nudity in film, both male and female.   The author/editor
is Craig Hosoda, and it's available on Amazon.com.

There are a couple of good scenes of Pierce Brosnan in the Thomas Crown Affair.
http://imdb.com/title/tt0155267/

Googlenut
AKA Big Pierce Brosnan Fan :-)

Have you seen Ewan Mcgregor in Long Way Round?

http://www.british-telly.com/longwayround.htm

He's not naked, but he gets very oily!