Many recent experiments probed the off equilibrium dynamics of spin glasses and other glassy systems through temperature cycling protocols and observed memory and rejuvenation phenomena. Here we show through numerical simulations, using powerful algorithms, that such features can already be observed to some extent in simple models such as two dimensional ferromagnets. We critically discuss these results and review some aspects of the literature in the light of our findings. Comment: 10 pages, 8 figures. Contribution to the Proceedings of the Summerschool "Ageing and the glass transition", Luxembourg 14-25 Sept. 2005