Apple - VNC Client that can send Ctrl+Alt+Delete?

The built-in Screen Sharing application on OS X is a VNC client that can send Ctrl-Alt-Del:

Laptop keyboard: fn+control+command+delete

Full-size keyboard: control+option+delete

If you are using a Mac and screen sharing on a Windows machine, use fn+ctrl+option+delete.

Apple Remote Desktop can send Control Alt Delete:

If you use Remote Desktop to administer a PC that's running VNC, you may be wondering how to send the Ctrl-Alt-Del command (Control-Alternate-Delete) from a Mac to the PC. Though Mac and PC key mapping differs, you can use an alternate key combination in Remote Desktop 2.0 and later to send the command.

For full-size (desktop) keyboards, use Control-Option-Forward Delete.

http://support.apple.com/kb/TA22781