Key of A: I-IV-V is A-D-E
Key of F: I-vi-ii-V-I is F-Dmin-G-C-F
move those two patterns around so you can play them in all 12 keys.
Thanks for your reply. Yet, I feel it's not quite what I was looking for. In order to train my ear and feel for the scales and the respective keys a little, I was looking for a chord or two that you could throw in into a key of G progression. Let's say you have a progression like this I, VIminor, V, IV (G, Em, D, C). I am now looking for a fine one or two chord cadence, that makes me leave the key of G for two measures and then come back again.