What's The Function? How to check if page is index
Design and Skin Customization
There isn't.
add {debug} into the template you're wanting to use it in and see what variables you have available. MAYBE there is something like template name 'index' or something like that that only shows up on the index page.
There could be something useful in the $_post array because that contains all the info coming from the address bar, so maybe something from there. I think it usually has a $_post['url'] or $_post['uri'] variable in it which could work.
Last idea is to define a variable on the index page:
{$my_variable = 'index'}