Traditional software needs installation. Online software has advantage that you can run it everywhere Internet browser is available, on each Internet ready computer, including some mobile phones, PDA, special car equipment, etc.

English language
Document readability
Learn English
Simple Basic English
Explain words
Understand English
Word frequencies
Vocabulary builder
Usage of words

Text tools
Online text analysis tool algorithm
Free text tools
Understand text
Frequent words
Misspell text
Text analysis
Unusual words

Webmaster and SEO
Free SEO tools
Keywords suggestion
Host and IP backlink checker
Anchor backlinks checker
Top paid AdSense keywords

Measurement
Measurements conversion

Math
Mathematic tools
Maths calculator
Small tutorial on math calculation