Written tutorials with screencasts, published by Tuts+.

EXCEL

How to calculate depreciation using Excel or Google Sheets

How to calculate present value & net present value using Excel or Google Sheets

How to calculate internal rate of return using Excel

How to extract data from a spreadsheet using VLOOKUP, MATCH and INDEX, using Excel & Google Sheets

How to format Excel spreadsheets using styles

How to create an Excel PivotTable using data from multiple sheets

POWERPOINT

Everything you need to make a basic PowerPoint presentation

How to use and edit master slides in PowerPoint

Inserting, drawing & editing motion paths in PowerPoint

Inserting & formatting videos in PowerPoint, and embedding videos from YouTube

How to control PowerPoint animation with the Animation pane

OUTLOOK

Tame your Outlook inbox with subfolders, rules and filters

How to set up your company e-mail with Office 365 hosted Exchange

WORD

How to create a table of contents in Microsoft Word

How to simplify Word document formatting with styles

ONENOTE

Getting things done with Microsoft OneNote

WEB

How to host your own webmail with Roundcube (article only)

Using advanced search techniques, mostly for Google and Bing