I am still thinking of getting this phone or not,
i have used Treo 650 and 680 before and i sold them after 2 weeks of use because they are too heavy and big compare with my Kyocera 7135.

I only use PIM functions on most parts, but i know i will lose a lot of good things without data plan on this phone, no internet no versamail etc.

But can i still do something fun like downloading emails and google map for offline usage on this phone? What are some of the good things I can still do without data plan?

I don't know about providers other than Sprint but on Sprint you want a data plan, even for email and Google Maps. The casual data rate for Sprint is something like 3 cents per KB which adds up pretty quickly (basically, once you have done 500KM in a month you might as well have gotten a data plan). Google Maps will want to open a data connection everytime you open it.

As far as fun things you can do, you still have the PIM functions, and the games and other 3rd party stuff like Open, Diddlebug, Docs 2 go, HandyShopper, Ptunes deluxe...