For TAS limits, there rarely are any as the required limits are covered by the IAS/Mach limits. However, the onset of flutter is by and large dependant on TAS.
One situation where this can become all too apparent is gliders flying in mountain waves. At the altitudes reached, the flutter TAS can easily be reached below the limiting IAS which, at for the aircraft type more normal altitudes, would normally prevent getting anywhere near flutter onset.
Those long slender wings can harbor a lot of interesting flutter modes, so glider pilots should be aware of their TAS.
As for what happens if you firewall the throttles at low altitude in a jet, I'd say flutter is unlikely to be the first problem you encounter. Your TAS will not be all that high after all. The drag caused by the dynamic pressures encountered will limit your acceleration.
However, the same drag due to dynamic pressure and the same forces which limit your acceleration will have an adverse effect on the structure of your aircraft. To put it another way, you may start shedding antennas, windshield wipers, landing gear doors, control surfaces and aerodynamic surfaces, probably in approximately that order.
In case this was posted earlier in the thread and I missed it, my apologies.
Rgds,
/Fred