as Blocking GoToMyPC:
Were I a system administrator, I would null route all of these services at the firewall, and would log any attempt to access them from within my network and kill the connection of the PC that attempted them - then proceed to LART the user that did so in a fashion that would make the BOFH wince. Their main purpose is to allow stupid lusers to do an end-run around the "meeny stupid-head network admin who won't let me access MY computer" (because he is doing his job of maintaining network security).
Although not a replacement for null-routing, GoToMyPC offers a free service where a company can register their Internet address blocks with GoToMyPC as not being permitted to register with the service.
(I've never tried this, not working in the kind of environment where you could just walk up to the CTO and say "Here, I think you should sign this".)
Any attempts to connect to the poll.gotomypc.com server are refused, and queries are redirected to the appropriate contact inside your company.
LogMeIn doesn't have an equivalent free service, they do provide something called "LogMeIn Scout" which claims to scan your network for remote access apps.