Tons of reasons with the main being Reagan sucking up NASA research money for Weapons development. Clinton recovered NASA only to hand it off again to an incompetent administration.
Reagan wasn't in office when we stopped going to the moon in the mid 70's. The main reason was the high cost of the Apollo program (which is indeed one of, if not THE greatest achievement in human history), and the need for newer, cheaper, re-useable spacecraft to more frequently travel to space to conduct experiments in micro-gravity environments, set up networks of communications and other types of satellites, etc...
The sad thing is.... today's annual NASA budget equals what we are blowing in about 6 weeks in Iraq.
We launched 2 vehicles this week to the moon with one probe which will beam back an entire mapping of the moon`s surface for a future manned mission by 2020.
Not yet. The Atlas rocket carrying these 2 vehicles was supposed to launch today (6/17), but it was pushed back to make way for the Shuttle Endeavor launch, which was moved to this morning after it was scrubbed last Saturday due to hydrogen leak. After range reconfiguration, the earliest the unmanned moon vehicles can launch is Thurs afternoon, but more likely Friday afternoon. Ironically, they should've left the Atlas on the 17th, as the shuttle was just scrubbed again due to another hydrogen leak, and now cannot launch until 7/11/09.