LifeHacker has been publishing e series of excellent resources for MS Office training.
http://lifehacker.com/tag/microsoft-office-week
http://lifehacker.com/top-10-cheat-sheets-to-help-you-master-microsoft-office-1768667500
http://lifehacker.com/everything-you-need-to-master-microsoft-office-1768495235
http://lifehacker.com/eight-useful-microsoft-excel-shortcuts-worth-memorizing-1767484423
I have always been fond of the tutorials at GCF Learnfree.
http://www.gcflearnfree.org/