During my time in PPC I have run across several (9 actually) tools from Google that could really make a difference in your marketing efforts, at least I think. I can’t promise you haven’t seen these before, but there might be something different here you haven’t seen, so check them out.

Trends- Here you get two great tools to work with. The first one is comparing sites, and keywords to see what is more popular. Secondly you get a list of the top 100 searches on google right NOW. Use this post to learn what to do with this information, it is great.
http://www.google.com/trends

Traffic Estimator- https://adwords.google.com/select/TrafficEstimatorSandbox with this tool you are suppose to be able to see how much traffic you could get on adwords for certain keywords, I believe it is just like the one you see in adwords, but I am not sure. Also I wouldn’t follow this too closely it can off, by quite a bit.

Ad Preview Tool-  https://adwords.google.com/select/AdTargetingPreviewTool – this is relatively self explanitory, you put in keywords and you can see your ads, sort of like on the regular search site, but I dont think it affects your impressions this way, not sure though, anyone want to weigh in on this?

Search-Based Keyword Tool- http://google.com/sktool/# This one is relatively new, and I am not 100% sure on how to use it. So I am going to link you to a couple of people who are sure. Search Engine Land |  Google Adwords Blog
Insights- http://www.google.com/insights/search/# I haven’t used this one either but I know that it exists and maybe some of you can come up with a clever way to use it.

Adplanner- https://www.google.com/adplanner/ I found this a few months ago and I love it. It reminds me of quantcast and alexa because you can learn so much about the site you put into it. This also helps when putting together marketing plans.

Keyword Tool- https://adwords.google.com/select/KeywordToolExternal I can’t tell you how much I love this tool for keyword research. To come up with related keywords, I use the bottom of the list. To come up with negative keywords I use the top of the list, and to come up with ppc keywords I use the whole list.

Analytics- http://www.google.com/analytics/features.html Find out what people are doing on your website, how long they are visiting, where they are coming from, the whole bit. Just about everyone serious about their site is using this, because it is free too.

Webmaster Tools- https://www.google.com/webmasters/tools/dashboard?hl=en Use this to submit your sitemap to get ranked faster. There is also the google conversion university here.