SSL is the recommended for securing client to server communications in SharePoint, following is a list of scenarios you might want to consider using SSL for

• Central Administration Site : Force portal administrators login to central admin via browser instead of remote desktop into server and secure central admin site using SSL, you can extend the central admin site to another zone and use SSL.
• Content Deployment : Content deployment promotes content from one farm to another, by default the communication is not secured, consider using SSL.
• Inter farm SSP’s: If you have child farms consuming SSP’s from parent farm consider securing using SSL
• Secure Collaboration with external partners: If you are hosting collaboration sites for collaboration with partners consider securing using SSL
• Remote Employee Access : If you have internal employees accessing intranet sites remotely consider securing using SSL
• Customers accessing and providing sensitive data: If you are hosting customer portals in your public facing farm for customers to access and provide sensitive data consider securing using SSL
• Sites configured to use Forms Based Authentication: If you are hosting sites in your farm that are configured to use forms based authentication consider securing using SSL