I use "LogMeIn" free, and that does allow it. In fact, someone can sit at the accessed PC and see stuff happening.
+1 for LogMeIn - 'er indoors had a minor problem sending an e-mail and I logged in to her pc from here in the States and sorted it out, plus she could "see" what I was doing on her screen and realised her mistake. It's a good program and the free version works well. The paid version allows one to transfer files between pc's.