I had 1 aborted landing, but the decision was made very early so no great increase in power (seemed like we were cleared to decend too late and were too high).

But I have had several aborted take-offs. My 'favorite' was when we started flying down the runway in our Embraer 145 and then suddenly aborted and the captain said '...we don't have enough power , we THINK it might be snow getting into the engines and reducing the power. So the airport is now closed while they clear then runway of snow and we will TRY again later'.

Luckily they were right and everything was OK, but we arrived at 03:30 after all the delays.