Advanced PHP URL Shortener is a powerful clean and lightweight script that allows your visitors to shorten their URLs, track hits and more. It also comes with an API that allows developers to get useful information such as shortened URL, original URL, accesses, date/time, elegant Metro design fully compatible with Android, iPhone and Windows Phone.

1. Custom Short URLs: Allow users to create custom short URLs, which can be more memorable and branding-friendly. Implement a system to check for and manage unique custom URLs to prevent conflicts.

2. Link Analytics: Provide detailed statistics on the usage of the shortened URLs. This can include information such as the number of clicks, geographic location of users, referral sources, and more.

3. QR Code Generation: Generate QR codes for shortened URLs, making it easy for users to share and access links using mobile devices.

4. Link Expiration: Allow users to set expiration dates for their shortened URLs, which can be useful for time-sensitive links. Implement a mechanism to automatically deactivate expired links.

5. Password Protection: Offer the option to password-protect URLs, ensuring that only users with the correct password can access the link.

6. API Integration: Create a RESTful API that allows developers to integrate your URL shortener into their applications, enabling automated link shortening and retrieval of analytics data.

7. Link Preview: Provide a link preview feature that displays a snapshot or metadata about the destination URL when users hover over or click on the shortened link.

8. Bulk Link Shortening: Implement a feature that enables users to shorten multiple links at once, saving them time and effort.

9. Link Management: Allow users to edit, update, or delete their shortened links. Provide a user-friendly dashboard for managing their URL portfolio.

10. Social Media Sharing: Integrate social sharing buttons, enabling users to quickly share shortened links on platforms like Facebook, Twitter, and LinkedIn.

11. Link Categorization: Allow users to categorize and organize their shortened URLs. This feature can be helpful for users with a large number of links.

12. Link Redirection Options: Provide users with choices for link redirection, such as direct (301), temporary (302), or masked (frame) redirects.

13. Geotargeting: Enable users to target specific geographic regions or countries for their shortened URLs. This is useful for marketing and analytics purposes.

14. API Rate Limiting: Implement rate limiting on your API to prevent abuse and ensure fair usage by third-party applications.

15. Spam and Malware Protection: Employ mechanisms to prevent the creation of malicious or spammy shortened links. Implement link scanning and filtering.

16. User Registration and Authentication: Create user accounts, allowing users to track and manage their shortened URLs more effectively. Implement authentication and user roles for security.

17. Link Previews: Show a preview of the destination webpage before redirecting users, enhancing trust and user experience.

18. Link Bookmarking: Allow users to save, organize, and categorize their shortened links for easy access and reference.

19. Traffic Routing: Implement intelligent routing options, such as redirecting users to different destinations based on factors like device type, location, or referral source.

20. Link Import/Export: Enable users to import and export their links for backup, migration, or sharing with others.