These are a selection of useful tools I use to help optimise websites.

Optimising press releases:
http://www.nowpublic.com/ – Excellent, quick & easy to set up.
http://www.pageflakes.com/ – Not used it yet…
http://forums.searchenginewatch.com/showthread.php?t=15966 – Interesting article on the subject of online press releases.

Page Rank:
http://www.iwebtool.com/pagerank_checker – Really good tool that displays PR from different Google datacentres.

Domains:
http://www.archive.org/web/web.php – This will show you when your domain was first issued. You can find out the “age” of a domain. A new domain can be difficult to optimise sometimes.

Page strength:
http://www.seomoz.org/page-strength/ – Cool tool to show how SEOMOZ rates the strength of a page.

Ranking Factors:
http://www.seomoz.org/article/search-ranking-factors – Comprehensive info on the important factors to consider when optimising a page.

Link Building:
http://www.seomoz.org/blog/every-site-is-linkbait-linkerati-worthy – Well informed article.

Let me know if you guys have found any good stuff.