I was caught a little off guard when noticing that I got new travel credits in this months online account activity (already had my $300 for the year several months ago). This forum and wiki helped explain, thanks (my next statement is in Jan).
However I'd thought I'd share what triggered the latest credits, I found it somewhat interesting what they counted as travel. We just got back from New Zealand and they gave me credit for HOBBITON MOVIE TOURS (great tour of the LoTR Hobbit village) and WAIOTAPU THERMAL WONDERLA (very neat thermal nature park). Also got the 3x credit for them. Fun data points!