MobileMe is a great service. It features services like email, calendar, contact management and more. It is fully integrated with OS X and even sports a nice web interface. It also costs $99 a year. This is exactly why I don't use it.
Instead, I have turned to Google Apps and other web bases sites for my cloud services. Here's a quick breakdown of MobileMe vs. Google Apps:
Email: MobileMe Mail vs. Gmail
Calendar: iCal vs. Google Calendar
Contacts: Address Book vs. Google Contacts
Find my iPhone: MobileMe vs. free Find my iPhone on the current iPhone 4 and iPad
Gallery: MobileMe Gallery vs. Picasa/Flickr/Facebook
Cloud Storage: iDisk vs. Dropbox/Crate/Amazon S3/FTP
While you won't get the tight integration that MobileMe provides, the free factor should motivate you to get it to work. Here's a post I wrote for Cult of Mac to give you the details on how I used Google Apps to replace MobileMe.
What I am trying to get at is that I feel Apple would gain so many more users if they just made MobileMe free. Wouldn't having free cloud services included with OS X make you want to switch to Mac or stay a Mac user for life? Making MobileMe free would be the best investment Apple would make in awhile.