Amazon.com has a good selection of autographed posters online, some framed, some unframed. You'll find signed sports, movie and art posters. Take a look at this selection here:

Michael Jordan Famous Foul Line Dunk Vintage Sports Poster Print - 24x36 Michael Jordan Famous Foul Line Dunk Vintage Sports Poster Print - 24x36
List Price: $40.00
Sale Price: $2.15

New Full Size Poster. High Quality. Suitable for Framing.
Steiner Sports MLB Caddy Shack Michael O'Keefe Autographed Movie Poster Steiner Sports MLB Caddy Shack Michael O'Keefe Autographed Movie Poster
List Price: $39.99
Sale Price: $27.09

Michael O’Keefe is best known for his role as Danny Noonan in the comedy film Caddyshack. The film centers around the story of Noonan, a caddy at Bushwood country club, with a series of mishaps and hysterical one-liners which earned the film a ranking on America’s 100 funniest movies of all time...
Upper Deck Authentic Michael Jordan Facsimile Autograph Framed Upper Deck Authentic Michael Jordan Facsimile Autograph Framed "Perseverance"
Sale Price: $14.99

This is for an awesome looking UDA Michael Jordan Framed piece! This item is 9 x 11 inches and is a framed picture of Michael Jordan in action titled "Perseverance." It features an awesome looking Facsimile autograph of Jordan and a quote about how he will turn something you think is a weakness into strength!! It is a UDA piece that was officially licensed by the NBA and originally retailed around $30! It comes ready to hang on the wall or stand on a desk...
TAYLOR SWIFT SIGNED AUTOGRAPHED ROLLING STONE POSTER JSA COA TAYLOR SWIFT SIGNED AUTOGRAPHED ROLLING STONE POSTER JSA COA
Sale Price: $249.99

NEW MUST HAVE MINT SIGNED POSTER 200% REAL WITH COA FROM JSA
Autographed/Hand Signed Music Poster: Enrique Iglesias Autographed/Hand Signed Music Poster Autographed/Hand Signed Music Poster: Enrique Iglesias Autographed/Hand Signed Music Poster
Sale Price: $98.95

Lightbox Size Autographed Enrique Iglesias Poster Individuals Signing: Enrique IglesiasSize: 22x34Co... Signed items come fully certified with Certificate of Authenticity.
Mounted Memories Chicago Bears Brian Urlacher Autographed Poster Mounted Memories Chicago Bears Brian Urlacher Autographed Poster
List Price: $299.99
Sale Price: $184.99

This Bear Hug poster has been personally hand signed by the Chicago Bears hard hitting lineback Brian Urlacher. This product is officially licensed by the National Football League and comes with an individually numbered, tamper-evident hologram from Mounted Memories®.
Autographed/Hand Signed Music Poster: Sting Autographed/Hand Signed Kodak Poster Autographed/Hand Signed Music Poster: Sting Autographed/Hand Signed Kodak Poster
Sale Price: $114.95

Autographed Sting Kodak Poster Individuals Signing: StingSize: 20x16Condition: ExcellentPrice: $87.... Signed items come fully certified with Certificate of Authenticity.
Sara Jean Underwood (Playboy Playmate) Signed Autographed 8x10 Photo (PSA/DNA COA) Sara Jean Underwood (Playboy Playmate) Signed Autographed 8x10 Photo (PSA/DNA COA)
List Price: $49.00
Sale Price: $44.10

This item has been personally hand signed by Sara Jean Underwood on January 7, 2010 under the direct supervision of American Icon Autographs. This item comes with an individually numbered; tamper evident sticker from the industries leading autograph authenticator PSA/DNA and comes with a lifetime guarantee...
Lady Gaga Signed Autographed Poster Jsa Coa Ga-ga Hot ! Lady Gaga Signed Autographed Poster Jsa Coa Ga-ga Hot !
Sale Price: $499.99

NEW MUST HAVE MINT SIGNED POSTER 200% REAL WITH COA FROM JSA