Check the following for activities to keep the children busy –

http://www.pinterest.com/search/pins/?q=rainy%20day%20activities%20for%20kids&rs=ac&len=9

http://www.pinterest.com/search/pins/?q=rainy%20day%20activities%20for%20toddlers&rs=ac&len=26

http://www.parents.com/fun/activities/rainy-day/