Here some recent list of really good tools for SEOs, webmaster and linkbuilders.
WARNING: Some of the stuff is extremely, extremely cool and helpful!!
This one is by far the best tool for checking backlinks and link strength. It lets backlinkcheck.com and others look old and outdated, believe it.
What is so good about it?
First off, it doesnt use the Yahoo siteexplorer API which 99% of the other sites use, therefore it doesnt count multiple links.
It does a very good and thorough check of backlinks and displays a ***load of stats, one of the best certainly backlink strength by using a formula which takes PR and outbound links into account.
This is pure gold for examining your own or competitor's backlinks! I simply love this!
The next gem is one of those "online site analysis tools" which is good for checking on site SEO. It checks your H header tags and many, many other on-site factors. It's also very simple and not overly loaded with useless features. At the end you get a score for your site. You can also download a report after the analysis
Don't let yourself get fooled by the plain interface, it is still very good for checking and improving your site!
In that same vain i need to mention Website Grader which i also use frequently for site analysis, it is also very good. It has a focus on the marketing aspect of your site and it analyses a lot of aspects of your site.
Get a visual graph of how Google sees the web with TouchGraph:
Touchgraph is simply spoken plain amazing. What it does: It shows graphically which sites are related afer you entered an URL or keyword.
It basically visualizes how Google sees the web and which sites it deems relevant for a keyword.
This way you can hunt and discover related sites, link to them and much more. Why is this helpful? Because for high SERPs you want to be "in" that trusted circle of relevant sites for your keyword. And here you clearly see which ones are relevant.
Compare your search results in Google to Google Caffeine: http://www.comparecaffeine.com/search-com.php
Another site which can be pretty helpful for the one or the other webmaster. It simply shows two windows, on the left classic Google and and on the right the Google using the new "Caffeine" algorithm. You might be surprised if you compare. Of course i hope that your sites have stronger SERP rankings in Caffeine as opposed to classic Google.
Auto Backlinks Submitter
This one is a little "hack" which will submit your site to a list of stat sites like alexa, quantcast and a zillion more:
Very good for getting your site indexed and getting backlinks from sites like alexa et al. Be advised it will spawn a lot of windows and will run until its finished. You simply enter your site www.yoursite.com or yoursite.com – click on "New Browser" and it will emulate a browser submitting your site to a few thousand (!) of stat and whois sites if you wish so.
The good thing: It creates backlinks this way, sometimes even with significant PR! Great way to get your site indexed.
I hope this little list is helpful for the one or the other webmaster or SEO.