Q:

How do i create tag cloud in Drupal 7?

I have found Drupal Tagadelic module. As of now, its not suitable for Drupal 7. 
Could you please any one tell me How do i create tag cloud in Drupal 7?

A:

You can get a static tag cloud with http://drupal.org/project/tagclouds. For a nice flash (dynamic) version, try the devel version of http://drupal.org/project/cumulus
EDIT
You can already use tagadelic for Drupal 7 for a dynamic tag cloud. It is available on github: https://github.com/berkes/tagadelic/tree/7.x-1.x
The Drupal7 branch is found there as well. It is reported as stable and usable, but needs refactoring and better testing until being released on drupal.org. 
Since tagadelic doesn't make changes to the database, only displays taxonomy, worst thing that could happen is that the page which displays the tag cloud crashes...

