Here is a pretty simple tool that I have found really helpful for some of the work that I do. I get leads from all over the country on my website. My web form, which feeds to web-to-lead in salesforce has a "best time to call" field that I added. I don't want to make the visitors to my web site fill out too much info because it tends to scare them away, so I only put a few neccesary fields - like the phone number, but I don't ask for time zone or city. However, if I'm going to call when they asked me to, I need to know where they are.
The easiest way for me to determine that is by doing a reverse number lookup on their phone number. I use the reverse number lookup on the whitepages.com website to find out the city and state of the lead. Then I know what time zone they are in.
That website allows you to feed the number you want to lookup in the URL. As a result, you can make a link or a button on your lead record, account record, or contact record that will automatically take the phone number stored in that record, send it to the whitepages website, and open up a page with the search results - big time saver.
Watch this video to learn how to set it up. The link you will need is included below.