I indeed have a rather elaborate scheme to fit my needs which include covering LATeX, but this is rather special to my German keyboard. I have in fact remapped the keyboard under Maemo, which carries over to debbie, while for LXDE I do it through xmodmap. Through xbindkeys I just get F1-F12, Escape, and Tab, and the full screen toggle.

A problem with Control+key is that many such shortcuts already exist in various apps running in Maemo. Control+t in particular is also used by firefox for browser tabs, and that shortcut would then be lost. I would instead argue for Shift+Fn+key, which we already have for F1-F12. Those are less likely to be used for other things and can rather easily be pressed simultaneously with one thumb once you get used to it. As an exception I would add Shift+Backspace for escape as advocated some time ago by debernadis. This is an important key in certain situations to get out of something. But with special symbols I think it's difficult to find a generally acceptable solution, because different national keyboards have different layouts as well as different selections of already included special characters. I would therefore only include keys that are missing for everybody. Tilde could be Shift+Fn+Space (in LATeX tilde gives space), Shift+Fn+t could be tab, Shift+Fn+p the pipe symbol, Shift+Fn+g the greater sign, Shift+Fn+l the less sign. Beyond those I would leave it to power users to set up their personal scheme.