Couple: Ellen DeGeneres (born Jan.26,1958) & Portia de Rossi (Jan.31, 1973)
Sun Sign: Aquarius vs. Aquarius
Venus Sign: Capricorn vs. Capricorn
Synopsis:
This outgoing couple love making friends, helping others, and on grander scale contemplate social change.   Ellen and Portia’s life together will never be boring, teacher they will try all the latest trends and fads. Together pets will be treated like royal members of the family. This couple gets along quite well, perhaps incurring the slight jealousies of all their friends. Sometimes, this couple has a great difficulty detecting or expressing real feelings, either their own, their partners or those of the people around them. Their similar goals and similar needs in love provide a healthy and solid foundation for your partnership.

EDITED
 

http://www.blacknews.com/blackcelebritygossip/images/will_smith_jada_premiere_legend.jpg

Couple: Will Smith (born Sept. 25th, 1968) & Jada Pinkett Smith (born Sept. 18, 1971)
Sun Sign: Libra vs. Libra
Venus Sign: Libra vs. Libra
Synopsis:
When two Libras come together in a love affair, they form one of the most agreeable, romantic and well-balanced relationships around. Libra is the Sign of Partnership; Libra loves to be in love, and two together spells relationship bliss. At their worst, both Will and Jada together can be a little bit unbalanced, both hating conflict, lacking focus and can together be quit indecisive.  The Libra-Libra duo understands this about one another and it’s rare that either one will push the other to compromise their shared sensibilities. To last both need to establish similar goals, devise a plan and stick to it– if someone stands up to be the "leader" in the relationship even better!

Note: I think Jada is the leader in this relationship, she must have a Scorpio somewhere in her natal chart she seems kinda masculine

 
http://www.wmagazine.com/celebrities/archive/brad_pitt_angelina_jolie?slide=12

Couple: Angelina Jolie (born June 4, 1975) & Brad Pitt (born Dec.18, 1963)
Sun Sign: Gemini vs. Sagittarius
Venus Sign: Cancer vs. Capricorn
Synopsis:
These are the best of friends and well-matched lovers for both share a deep understanding and similar life view filled with many great adventures. Any rough spots they encounter are sure to be smoothered over with minimum effort thanks to both of their refreshing optimism and enthusiasm. Brad can be too blunt at times and more practically inclined, however sensitive and intuitive Angelina can forgive and foget easily. Both have attention spans that love to move quickly from one thing to the next in order to absorb as much experience as possible. This is a great match — Gemini comes up with a new idea and Sagittarius jumps right on, ready to explore it to its limits. However, Angelina and Brad must learn to appreciate each other’s differences rather single them out and use them as emotional weapons against each other. Dependability and personal independence will characterize this pairing and luckily for both this is a very important trait both are looking for.

http://chicinparis.files.wordpress.com/2007/07/tom-cruise-and-katie-holmes.jpg

Couple: Tom Cruise (born July 3, 1962) & Katie Holmes (born Dec.18, 1978)
Sun Sign: Cancer vs. Sagittarius
Venus Sign: Aquarius vs. Sagittarius
Synopsis:
When Cancer and Sagittarius make a love match, they both need to be patient and give the relationship time to grow and mature; as it does both will realize they have much to offer each other.   Double Sagittarian, Katie Holmes is more of an thrill seeker and free spirit, while "Crazy" Tom derives more satisfaction from emotional security and tradition. Early on in the relationship Tom  might have wanted more commitment than Katie was willing to give. Cancer’s emotional tidal wave can be difficult and overwhelming for Sagittarius to accept.  If both can get beyond their minor incompatibilities, and treat them as an opportunity to grow this relationship can last. Tom can offer Katie a secure home base to keep their dreams, ambitions in perspective, and Katie in return can give Tom’s daily life a little more diversity and excitment.

Source: Me well mostly www.cafeastrology.com and astrology.com