Whether you want to shift your Outlook to the cloud, or want to import data from the cloud into Outlook, or just want to keep your Outlook items in sync with an online service*, here are some free tools / web services to help you out.
Sync your Google Calendar with Outlook
Google provides an official Outlook addon to help keep your Outlook calendar and your online Google Calendar in sync with each other. Using the add-on, you can either copy your Google calendar to Outlook (and vice-versa) or use the two-way sync option to keep both of them in sync always.
Sync your Outlook Address Book with Google Contacts
If you would like to keep your Outlook Contacts in sync with Google Contacts, get GO Contact Sync. This is an open-source tool that can synchronize not only the contact details but also their profile pictures. If you have created address books across multiple services, you can use this tool to merge them all and create a master contacts list.
Migrating from Outlook to Google Apps
If you simply wish to copy all your emails and contact information from Outlook into your online Google Apps account, you can use the free Mail Uploader program that is available for Windows XP and Vista. The tool will move your Outlook data into Google Apps in one step but your accounts won’t stay in sync later. You can either upload your entire Outlook mailbox to Google in one go or select specific Outlook folders before initiating the upload process.
Sync Windows Live Hotmail with Outlook
If you use Windows Live services (like Office Live or Windows Live Hotmail) to manage your online email, calendar, and contacts, you can use these same services in Outlook using Outlook Connector.
Simply install the addon in Outlook, sign in with your Windows Live ID, and all your emails contacts, and calendar events from Windows Live will be downloaded and synced with Outlook for free. You can also use this add-on to copy all your existing Outlook items into Hotmail.
Sync Outlook Contacts with your Phone Address Book
If you maintain separate address books on your mobile phones, Outlook and on multiple web-mail services, Soocial can help you merge them all. Soocial will also remove duplicate contacts from your different online accounts, and will also let you download a backup copy of your contacts if you ever need to.
Outlook Sync For Google Apps
If you are using Google Apps at work, you can grab the Google Apps Sync add-on to sync all your email messages, calendar items, and contacts in Outlook with your online Google Apps account. The Apps Sync add-on makes Google Apps act more like an Exchange account as you can manage all your data from within Outlook as well as from your online Google Apps account online. Google Apps Sync is only available with the Premier Edition of Google Apps.
Connect Outlook with Office Live Workspace
You can export Contacts List, Events, and Task List from your online Office Live Workspace account to a local folder in Outlook
[*] You can use BlackBerry Desktop Manager with IntelliSync to sync your BlackBerry with Outlook while iPhone users can sync with Outlook via iTunes.