Seobay recommends these SEO tools:
Keyword Research
1. Google
Adwords Keyword Tool
2. Overture
Keyword Selection Tool
3. Wordtracker
Keyword Concept
Link Popularity Checker
1. Link
Popularity Checker
2. Another
Link Popularity Checker
Future Pagerank Estimation
1. SEOChat
Future Pagerank - Based on datacenters
2. iWebTool
Pagerank Prediction
Pagerank Based Search
1. Shows
pagerank of search results
Domain Information/Whois
1. Whois.sc
Other Good SEO Links
1. SEO Tips
2. SEO Book
3. Keyword
Typos
4. Keyword
Density Finder