When creating webapps, is there any guidelines on which keys you can use for your own hotkeys without overriding too many of the browsers default hotkeys.

For example i might want to have a custom copy command for copying entire sets of data that only makes sense for my program instead of just text. The logical combination for this would be ctrl+c but that would destroy the default copy hotkey for normal text.

One solution i was thinking about is to only catch the hotkey when it "makes sense" but when you use some advanced custom selection it might be hard to differentiate if your data is focused, if text is selected or both.

Right now i am only using single keys as the hotkey, so just 'c' for the example above and this seems to be what most other sites are doing too. The problem is that if you have text input this doesn't work so good. Is this the best solution?

To clarify I'm talking about advanced webapps that behave more like normal programs and not just some website presenting information(even though i think these guidlines would be valid for both cases). So for the copy example it might not be a big deal if you can't copy the text in the menu but when ctrl+tab, alt+d or ctrl+e doesn't work i would be really pissed, cough flash cough.