This post help you to get url, directory path, to get module URL. This is very basic post, that will help to beginners.

Get Base URL

Mage::getBaseUrl() => Get base url path
e.g. http://yourwebsite.com/

Mage::getBaseUrl(‘media’) => Get MEDIA folder path
e.g. http://yourwebsite.com/media/

Mage::getBaseUrl(‘js’) => Get JS folder path
e.g. http://yourwebsite.com/js/

Mage::getBaseUrl(‘skin’) => Get SKIN folder path
e.g. http://yourwebsite.com/skin/

Get Current URL

Mage::helper('core/url')->getCurrentUrl();

Get Home URL

Mage::helper('core/url')->getHomeUrl();

Create module your

Mage::getUrl('module/controller/action');

Get secure URL
To get secure URL you just need to add one more parameter as bellow,

Mage::getUrl('',array('_secure'=>true))
Mage::getUrl('module/controller/action',array('_secure'=>true))

Get Directory paths

Mage::getBaseDir()
 //output : /var/www/html/magento
Mage::getBaseDir('app')
 //output : /var/www/html/magento/app
Mage::getBaseDir('media')
 //output : /var/www/html/magento/media

Same way you can get more directory path,
Mage::getBaseDir(‘design’) => Get design directory path
Mage::getBaseDir(‘code’) => Gives code directory file path
Mage::getBaseDir(‘lib’) => Gives lib directory file path
Mage::getBaseDir(‘skin’) => Gives skin directory file path
Mage::getBaseDir(‘var’) => Gives var directory file path
Mage::getBaseDir(‘cache’) => Gives cache directory file path
Mage::getBaseDir(‘log’) => Gives log directory file path

Get URL path in Static Block
Get Base URL

{{base url=''}}

Get Skin URL

{{skin url='images/skinimage.jpg'}}

Get Media URL

{{media url='/mediaimage.jpg'}}

Get Store URL

{{store url=''}}