The following code gives you the current url of the page you are:-

$currentUrl = $this->helper('core/url')->getCurrentUrl();


// Gives the base url of your magento installation
$baseUrl = Mage::getBaseUrl();


// Gives the url of media directory inside your magento installation
$mediaUrl = Mage::getBaseUrl('media');

Another way to get current url

$urlRequest = Mage::app()->getFrontController()->getRequest();
$urlPart = $urlRequest->getServer('ORIG_PATH_INFO');
if(is_null($urlPart))
{
    $urlPart = $urlRequest->getServer('PATH_INFO');
}
$urlPart = substr($urlPart, 1 );
$currentUrl = $this->getUrl($urlPart);

Related posts:

1. Magento: How to check if current page is homepage?
2. Magento: Easily add breadcrumbs to any page
3. Magento: Convert Price from Current Currency to Base Currency and vice-versa
4. Magento: Get current and parent category
5. Magento: Resize Image
6. Magento: Get width height of image using Varien_Image class
7. Magento: Create CMS Page & Static Block programmatically
8. Magento: Solution to “Error: 404 Not Found” in Admin Login Page
9. Magento: Custom function to resize image proportionally
10. Javascript: How to get current URL without Query string?