equipment recommendation - Is there a good remote timer compatible with most Nikon and Canon (and Pentax and Sony) cameras?

I wish to experiment with HDR night photography and timelapse video editing. Both require me to take multiple shots are regular intervals for prolonged durations, and I obviously do not wish to sit there with a manual remote clicking every shot.

I am currently using a Canon Powershot G12, and from what I understand, I need either to flash my device with CHDK (to get a builtin intervalometer), or get an external remote timer. I am leaning towards the second alternative, as it will be more flexible in the long run and CHDK seems to be difficult to setup on the G12.

I have seen universal timers on Amazon.com that are seemingly compatible with every camera on earth - or at least the ones I care about, namely the Canon G12, Canon 5D Mark III, Nikon D300 and D7000.

What are your experience with those devices? Is it realistic to expect fair performance and reliability from such universal adapters? Why would I even buy a timer that is not universal considering the price differences?

Are there any ways of doing timelapse photography on the G12 that I am missing? :)