Is There any tool to convert any template (wordpress, joomla, static html/css etc) to a drupal theme
There is, however, a nice page full of information to convert Drupal 6 themes to Drupal 7: link
I don't think there is an easy way to convert a "template" into a Drupal theme. At least not something that is going to do all of the heavy lifting for you. If you are new to Drupal, start with a base theme, such as Fusion, Adaptive Theme, Omega or Zen and that will give you a good start. And depending on the complexity of the theme, you can sometimes get away with doing just css.
Themeing also just got easier in 7. I have recently been experimenting with pure css themes and its works nicely and keeps it lightweight.
As far as I know, there is no easy process to convert a custom html/css project into a Drupal theme. One of the reasons is that a Drupal theme needs to have files that describe how specific blocks look like, Views etc and that's not something that you can easily automate: someone knowledgeable needs to do the conversion.
However, if you have some time and you would like to try some things out this podcast, helped me a lot when I started theming back in Drupal 6.
The basic ideas remain the same, but a slideshow that I found about some of the new things in D7 theming, can be found here.
Ideally, you want to watch the whole podcast that I mentioned above, and then, after getting the idea of Drupal Theming in general, you can check the slides for some more D7-specific information.
I think there is not such tools of converting form Drupal x to Drupal 7. Theoretically, the process is not so complicated (depends of your theme practically) you can do it yourself following the suggestion of @Alex.
However if the question is to convert form WordPress, Joomla and other themes to Drupal there are nice tools to create a Drupal theme such as Artisteer and maybe it will convent also.