Five Google Tools You Should Know
Google Adwords keyword tool: Generates search volumes and variations of your keywords. https://adwords.google.co.uk/o/Targeting/Explorer
Google AdWordsSearch Based Keyword Tool: See what keywords are on your site that people are already searching with on Google with this tool that compares your website content to actual search queries. Now part of Google Adwords keyword tool.
Google Insights for Search: Reports search trends over time. www.google.com/insights/search
Google AdWords AdPreview Tool: Preview your ads in real time as they appear on the search results. https://adwords.google.co.uk/d/AdPreview
Google Website Optimiser: Optimize your landing pages by evenly splitting web traffic between multiple pages to compare performance. www.google.com/websiteoptimizer