I stumpled upon this great tool from SEOmoz to measure your Page Strength, a measure made by checking various things like inbound links, popularity, mentions of your page across the www.
The tool gives you a relative importance / visibility of a webpage.

I belive this tools is way better to determine how strong a page is, whereas PageRank only gives you a measure of the inbound links
Aviva directory has made a collection of various paid directories and their link strength. Check them out

Technorati Tags: PageRank, Directory, Link Strength, SEO Tool

When developing websites, and especially optimizing them, its a good thing to have some usefull tools.

http://www.iwebtool.com/ 
These guys have a good selection of tools for webmasters. I can mention:

• Domain lookup
• Website speed test
• Reverse IP lookup
• Ping tests
• Link extractor
• Meta tag extractor
• Pagerank prediction
• Backlink checker
• Link popularity

And alot of other tools.
They also offer webmasters to incorporate theese tools on your own page, so you can give this service to others from your site. That is a sweet feature

http://www.linkvendor.com/seo-tools/domain-popularity.html
This is a great Domain Popularity checker from LinkVendor.
You can easily cross check searchengines for backlinks and strength on your site (or your competitors )

http://www.backlinkwatch.com/
Quite good backlink checker. I like the output, even though it takes some time to get through all links.

Technorati Tags: SEO, SEO Tools