Tink Sound NOT Creak

Have you checked your spokes, or had them checked, for correct tensioning? They can rub against each other if they are slightly loose or have different tensions and can cause a small tinking sound when under a power load.

If they have been tensioned recently you might also need to de-stress them http://www.sheldonbrown.com/wheelbuild.html#seating

I hope it's not, but have you checked the frame carefully for any cracks?

We're getting to the earplugs and just ride stage now

The mech hanger one is a good suggestion, it ties in with my comment about back-pedalling and checking for rear mech kick as that's a good mechanical check for an out of alignment mech hanger.

Have you tried tightening the gear hanger bolt? Also, grease the bolt and a little bit of grease on the back of the hanger between it and the frame

Have you tried cleaning your pedal contact areas and cleats ? Look are no toreros for clicking....sometimes they do sometimes they don't ! I spray a little GT85 and wipe...sorts it out !

also had a ticking noise that turned out to be the front skewer...bit of grease now it's sound .

feel your pain....ticking creaking is the most annoying part of cycling....other than the weather !

What happens if you put the bike on the stand with the chain on the largest cog at the rear and largest at the front and then back-pedal? Any kick from the rear mech? That combo puts max stress on the drivetrain and can show up a B-screw tension issue. Unlikely to encounter it when pedalling forward so really clutching at straws but rule it out..

If you can try putting the pressure down when riding with hands off the bars. The aluminium forks were acting like an amplifier, there was no noticeable play on the front QR, but once greased and really tightened, "Voila" a silent bike.

I notice that you said you had checked the rear QR, but I have seen numerous occasions when this sort of noise can be caused by a front QR too. 

Try removing the QR, clean it and lube the cam surface and re-fit, making sure it is fairly tight (Shimano say it should leave an impression on your hand when you close the lever). Also check and clean the fork-ends and hub faces just incase there is some contamination.

QRs were responsible for so many creaks and sounds that bikes came in to me for.

Are you doubly sure you've ruled out the chainring bolts and ring interface? Road.cc reviewer and all round mechanicing beard KiwiMike reported something similar a couple of months ago that was to do with the chainring interface. Could you borrow a chainset to rule it out? 

I had this problem and spent a whole ride getting on and off not quite understanding what the problem was. My tink was a loose cleat screw

Have you tried adjusting the front mech? Might sound  a bit silly but i spent ages trying to track down a tick on my old giant bike,it eventually stopped after i set the limits slightly wider (just a tad) and fiddled around with the barrel adjuster.That was a triple though.

Had the most annoying tink sound on my Whyte, replaced bb and spent ages checking thru the drive train, regreased, retorqued etc. Seemed to do it when the right pedal was on the down stroke. Eventually traced it to the front wheel QR, it really did sound like it was from the BB.

Try checking your chain for broken end plates, i had more of a clunk than a clink but mine is on a carbon bike and could sound differently on ally, i knew mine was drivetrain related and thought it it had something to do with the rear wheel , took me a few days to track it down and took out the offending link and  put in a quick link and problem solved.

You say on the "power stroke". Is that on both pedals, or just the one? If just the one, which one?

I've had a "tink" when the right crank was brushing past the front mech cable. The cable then pinged back as the crank passed, dinging against the downtube.

cable end cap from front mech on the crank arm? I've had that.

I had a 'tink' going on when I pedalled.  Took me a while to work out that the outside of my front mech was just being touched  by the crank arm.  Even when re-adjusted the SRAM Red mech and the Cannondale crank have a very small clearance.  It is even more of a pain in that the limit screws seem to move occassionally.

Hope you find yours.

Front mech cable contacting wheel/rim? Outside chance but if its a long arm one (e.g. 5800, 4700) then it can do it. Mine (which I must shorten up) is only about 5mm from the rear tyre.

Ditto for rear mech cable although that's even less likely

Have you checked that the rear mech is not touching a spoke, as you say it is in the larger sprockets?

It may not show up in the stand with no load if this is the issue, as when you are pedaling, the wheel will tend to deflect and the drive side spokes can bow out slightly under load. 

It could be an out of line mech hanger or mech cage.

If it consistently coincides with a pedal stroke (is it just on one side?) the most likely is chainring, BB or the pedal itself.

Mine (square taper FSA chainset & BB, SPD pedals) does it sometimes but I CBA to do anything about it just now.