Issuetrak - Issue tracking software for help desk and customer service
TeamViewer - TeamViewer lets you establish a connection to any PC or server within just a few seconds.
Deskun - Deskun is a Help Desk system inside Gmail. It enables you to support customers directly from your mailbox, manage projects, and use free features for Gmail.
LogMeIn - LogMeIn gives you fast, easy remote access to your PC or Mac from your browser, desktop and mobile...
Kapdesk - Kapdesk offers support teams with a helpdesk software to streamline support tasks.
UltraVNC - VNC remote access software, support server and viewer software for on demand remote computer support. Remote desktop support software for remote PC control. Free