Here is a list of 39 tools which can help you to look for your search trends, keywords and topics.
1. Google Trends
http://www.google.com/trends/
2. Hot Searches
http://www.google.com/trends/hottrends
3. Yahoo Trending Now
http://news.yahoo.com/blogs/trending-now/
4. Yahoo Clues
http://clues.yahoo.com/
5.Aol Serach Trends
http://search.aol.com/aol/trends
6. Bing Search
http://www.bing.com/blogs/site_blogs/b/search/archive/2012/11/26/year-end.aspx
7. Bing Keyword Research
http://www.bing.com/toolbox/keywords
8.YouTube Keyword Tool
https://ads.youtube.com/keyword_tool
9. YouTube Trends
http://youtube-trends.blogspot.com/
10. Twitter Search
https://twitter.com/search
10. Google Adwords Keyword Tool
https://adwords.google.com/o/Targeting/Explorer?__c=1000000000&__u=1000000000&ideaRequestType=KEYWORD_IDEAS
12.KeywordEye
http://www.keywordeye.com/
13. KeywordSpy
http://www.keywordspy.com/
14. SEMRush
http://www.semrush.com/
15. Keyword Density
http://tools.davidnaylor.co.uk/keyworddensity/
16. Ubersuggest
http://ubersuggest.org/
17. Mergewords
http://mergewords.com/
18. Xenu Link Sleuth
http://home.snafu.de/tilman/xenulink.html
19. Wordtracker Free Keyword Tool
https://freekeywords.wordtracker.com/
20. WordStream
http://www.wordstream.com/
21. Google Suggest Keyword Scraper Tool
http://tools.seobook.com/general/keyword-information/
22. Google Suggest
http://www.google.com
23.Soovle
http://soovle.com/
24.SEO Book Keyword Tool
http://tools.seobook.com/keyword-tools/seobook/
25. Good Keyword V3
http://www.goodkeywords.com/good-keywords/
26. Trellian Search Term Suggestion Tool
http://www.keyworddiscovery.com/search.html
27. KGen
https://addons.mozilla.org/en-US/firefox/addon/kgen/
28. WordPot
http://www.wordpot.com/
29. Wordtracker Keyword Questions
https://freekeywords.wordtracker.com/keyword-questions/
30. GoRank
http://www.gorank.com/seotools/ontology/
31. SpyFu
http://www.spyfu.com/
32. PPCSpy
33. Traffic Travis
http://www.traffictravis.com/
34. Keyword Country
http://www.keywordcountry.com/free-keyword-tool/
35.Open Site Explorer
http://www.opensiteexplorer.org/
36. AlexaSite Info
http://www.alexa.com/siteinfo
37. Keyword Playground
http://webconfs.com/keyword-playground.php
38. Keyword List Generator
http://tools.seobook.com/keyword-list/generator.php
39.SERPAnalytics
http://www.serpanalytics.com/tools/top_keywords
