It is important to take the backup of the mobile phone contacts, SMS, Email everything in regular interval. Taking the backup helps you to easily recovery your valuable contacts if you want to change your handset or by chance mobile damaged etc,.
You can use the google sync application to take the backup of your mobile phone contacts, calendar and push sync support. Google sync supports nokia, Blackberry, Iphone and windows mobile handset.
Check mobile online backup software for more about different online backup software
Note: Usage of online mobile contact backup software may train your mobile battery quickly. Because it will sync the contact in regular interval so it consumes lot of battery backup. Be careful to set the interval to 1 day or more based on your usage.