1. Echosec. Without doubt , one of the best tools I have come across. Tracks and geo locates tweets, instagram, flikr, etc. Long range searches in the past, realy nice interface. There is a limited free version for you to have a go. The paid has additional features. Very expensive and restricted to open accounts only, but worth checking out.
2. HEXILLION. Also called central ops. Your first port of call if you have an IP , URL or Tld you need to find out what is recorded on the system about it. Its registrant, date, expiry, server, Host, ttl, the list goes on. If you havent done a search on this as your first task, youre missing something.
3. WIGLE. Do you have an SSID, MAC or wifi access point name? Put it into the searchbox at wiglle.net. It has an up to date mapped database of EVERY public wifi access point on the planet. If your guy used a public wifi access point, Wigle will tell you where that is, and show you a map. Very powerful, but if you dont have a fast internet access, can be a bit slow as its so vast
4. METACRAWLER. We all have our favourite search engines, but they all search the internet in different ways, and therefore get different and varying results. Did ypou know Google only returns 12% of the internet in its search? Metacrawler searches the search engines. It maynot be 100%, but its search area is better than individual ones. Break the habit and use metacrawler.
5. Usersearch. A deep web scrape tool that will find usernames and hashtags on the web. If its there , Usersearch will probably find it. Loads more useful tools built in as well. Still in development stage, but if this is anything to go by so far, its gonna be the best. Probably the best help you can get, and getting better
6. EMAIL TRACE. Email heasders are perhaps the most overlooked source and missed opportunity by any investigator. Their value cannot be understated. If you cannot read headers, use this tool to decypher them into a readable and visual tracker, to enable you to understand how it moved, but more importantly where it was sent from amd what servers will hold the information you seek
7. NUMBERING PLANS. If you have any data relating to a mobile phone, or sim, this is a one stop shop for everything ; IMSI, IMEI, SIM, ISPC. If you have any of these available, this site will assist to IDE where the sim was issued, what network, the phone it is in ( and what that phone can do), if its in a dongle or other non telephony device. Very useful site
8. INFOSNIPER. Excellent geolocation tool. Search any IP and it will locate either the server or the final exit point allocated to that IP, which can be to within a few hunderd metres of the IP's location, depending on the provider. Very useful tool if you want a quick and dirty "where in the world are they". Also provides grid reference to tie it down a little more accurately.
9. TINEYE. Excellent Image search tool . Upload a saved image or enter the URL and Tineye will search the web for every location of that image. Very powerful and useful if you have an image that you are trying to identify the person in it, as it will scrape SN sites and if your subject used the image on their page, you will find them.
10. Onemilliontweetmaps. . Does what it says. Geolocates tweets upto 6 hrs old. Has a useful keyword search option. Nice, but limited to twitter.