Let’s get right to it, shall we?

Keywords/Trends

1. Keyword Discovery – for all the keyword research you could ever care to know. It does require a subscription – this or Word Tracker (which I’ve never tried) are considered the best.
2. Google AdWords Keyword Tool – supplement keyword research; also gives better stats as to what people are actually searching for.
3. Webconfs.com Keyword Density Tool - there are a million keyword density tools out there, but I’ve found this one to be the most user friendly.
4. Google Insights/Google Trends – both give good insights as to what’s hot and what’s not.  Insights will also give you upcoming popular search terms.

Link Building

1. Marketleap’s Link Popularity Checker – gives you both Google and Yahoo!’s index of backlinks, plus others.

Plug-ins and Apps

1. SEO for Firefox – see nofollow links; look up PR, backlinks, meta-tags; plus much much more!
2. SeoQuake – many of the same benefits as SEO for Firefox, but you don’t necessarily have to have Firefox.  Plus, when activated, SeoQuake will give you a handy little toolbar with at-a-glance SEO stats.

Analytics (the one and only)

1. Google Analytics – it’s free and gives you everything you need.  Why go for something else??

I use quite a few more, but these are my favorite, and the ones I use the most often.  Do you have any favorites?

Nicki Hicks
I think I need a bigger toolbelt…