1. Google Adwords Keyword Tool
Probably the most important tool in the armoury of a Pay Per Click account manager, this tool will tell you derivative keywords, search volumes, ad positions and approximate CPC's. You can target by area and also by match type. Since the overture keyword tool's demise, this is now the number one free keyword tool on the web.

2. Google Traffic Estimator
This tool gives you approximate search volumes based on keywords that have been entered. The one drawback from this tool is that its accuracy is questionable. However, it's the closest your gonna get to knowing your click volumes in advance of a campaign. It can be adjusted to target languages or countries and also shows ad positions based on CPC's and budgets.

3. Preview My PPC
This is a great tool for previewing how your ads will looks on Google, Yahoo and MSN. Although not particularly useful as any experienced account manager will be well accustomed to the different formats, it is brilliant for taking screenshots to show to clients and potential clients.

4. Adwords Editor
Okay, so not technically a tool but a must all the same. Fast, easy to use and completely free of charge this application was coded by Mozilla. Bulk uploads and changes can be made in seconds. Yahoo and MSN would be wise to follow suit!

5. Adwords Wrapper
Nice tool that automatically creates phrase and exact match keywords from your list. Handy if you still upload using Adwords rather than Editor.

6. Adwords Preview Tool
The Adwords preview tool lets you view your ads without generating an impression in your account. This is useful if you often check the same keywords as doing so without using this tool can artificially push your ad down the page. Also useful if you are using geo targeting and want to check if your ads are displaying in your chosen area.

7. MSN Demographic Prediction
Want to know if your audience is mostly male or female? If it will impact on your adcopy, then use this tool to show how many of the searchers are male and how many are female. The data may come from MSN passports, so its accuracy is somewhat questionable.

8. Spacky
Useful tool for getting estimates of searches on Google, Yahoo and MSN. The Overture data might be inaccurate as Yahoo disbanded the public use of the tool sometime ago. There is also no geo targeting option.

9. Miva Keyword Tool
This keyword tool is useful because you can automatically see lists of derivative keyterms and the derivatives of them. So for example if you query "Loan" a list of loan related terms appear. If you click on one of the words on the list, such as "Pay Day Loan", you can see all the derivatives of "Pay Day Loan". Useful for categorisation when building a new PPC account.

10. Misspelling Tool
Occasionally users will not type a keyword in correctly (shock). So it can be useful if you have keywords that are often misspelt, such as "Chandelier" which will have a multitude of spelling attempts.