Blogging: Darren Rowse's A to Z of Professional Blogging (IV)

N
NewsGator - RSS News Readers
Nichebot - keyword research tool
Nameboy - domain name generator
Nucleus CMS - open source blog platform
Netvibes - RSS News Aggregator
Netscape Beta - Social Bookmarking Tool

O
Only Wire - social bookmarking service
Overture Keyword Tool - keyword research tool

P
Performancing - great blog, firefox blog editor and metrics tools
Pheedo - RSS advertising
Post2Blog - Blog Editing tool - blog using Word, IE or Firefox
Pingoat - Pinging Tool
Pingomatic - Pinging Tool
pMachine - Blog Platform
Paypal - Payment tool - used by many affiliate programs and ad systems to pay publishers
PPCalc - Paypal Fee Calculator
PubSub - service that notifies you of new content
Photobucket - image and video hosting

Q
Qumana - Blog Editing Tool

R
Rojo - RSS feed reader
RocketPost - Blog posting tool
Right Media - advertising
Rmail - subscribe from any RSS feed to email

The full post.