MobileMe is a service provided by Apple that allows you to do numerous things, primarily Mac related, but also has Windows support. One of the main features is Mail. You get your own email address that has a format like this: [email protected]. You can choose to view it off of the MobileMe web interface or by email clients such as Apple Mail. Another great feature is the photo gallery where you can upload and store photos for your own safe keeping or for public view.
Alongside the photo gallery, you also have a file sync service called iDisk. By default, you have about 20 GB of storage with a 200 GB per month transfer limit. This can be upgraded up to 60 GB of storage with 600 GB per month transfer limit. This is really good for backing up files to a “cloud” source, rather than a hard drive.
Another great feature that MobileMe offers (Mac only) is Sync. You can sync your Address Book and iCal for viewing on the MobileMe web interface. Besides Address Book and iCal, you can also sync Safari Bookmarks, Dashboard Widgets, Dock Items, Keychains, Mail Accounts, Notes and System Preferences. This feature is really nice if you are wanting to put the same things on a new Mac or if you are looking to format your current Mac and reinstall OS X.
A few more features include a personal domain in which you can create a personal website with iWeb, Security Certificates for iChat encryption and Back to my Mac encryption, and finally Find my iPhone for the ability to pinpoint the location of your lost iPhone. Along with finding your iPhone, you can send a message or sound to it, lock the phone and remotely wipe the memory off of it. Overall MobileMe is a great service to use and I strongly suggest it. The only problem with it is that the price is a bit high, starting at $99 per year.
If you have that kind of money to spend, then go for it because it is a great service.