Summary of actual Missions
(click on the link to learn more about each mission...)

launch: February 17, 1996

Ast. Mathilde fly-by June 1997
Ast. Eros Flyby December 1998
Ast. Eros Rendezvous February 2000

The Near mission flew within 1200 km of asteroid Mathilde and spent nearly one year in orbit about asteroid Eros...

launch: October 25 1998

Ast. Braille fly-by July 1999
Com. Borrelly fly-by September 2001

The primary Deep Space 1 mission objective is to test space technologies. In doing so, the spacecraft has made a fly-by of asteroid Braille and was targeted to 2 comets.
launch: February 6,1999

Com. Wild-2 fly-by January 2004
Earth sample return January 2006
Stardust will image the nucleus of Comet Wild-2, collect dust from both the comet's coma and from interplanetary space and bring these dust samples back to Earth for study.
launch: August 13, 2002

Com. Enckle November 2003
Com. SW3 June 2006
Com. d'Arrest August 2008
Contour will image and study the nuclei of three different comets. Should a bright, new comet be discovered in time, the spacecraft could be retargeted to study this new comet.
launch: November 2002

Ast. 1998 SF36: September 2005
Earth sample return: June 2007
Muses-C spacecraft will rendezvous with a near-Earth asteroid, drop off a small rover and return asteroid surface samples to Earth for analysis.

launch: January 2003

Ast. Mimistrobell fly-by September 2006
Ast. Rodari fly-by May 2008
Com.Wirtanen landing November 2011
After flying by two asteroids, Rosetta will rendezvous and land upon the surface of a comet in an effort to study its composition and structure.
launch: January 6, 2004

Com. Tempel 1 impact July 2005
Deep Impact mission will impact the surface of a comet to study the crater formation process and examine its subsurface structure.

Here is also a summary of past missions that made observations and measures (direct or indirect) on NEOs. Among them there are some very known missions such as Giotto or Galileo...