Not exactly an island event but how about linking up fish tycoon and village. Example for those who play fish tycoon and village sim on the same computer: if you find a magic fish, you can research points in village sim. And if you gain research level 2 and 3 in village sim, the time it takes to research environment, advertising etc. on fish tycoon speeds up.

BTW, will plant tycoon move onto PC? If so, can I request for two things:
1) The ability to click on a plant and show its parents (grandparents would be even better!)
2) More boxes to contain seeds and more flower pots ....

Regards,
SBB