I don't believe XenForo has this capability yet, but it'd be a really cool mod. I'd like there to be a feature like Google Alerts where you would get an Alert here on DigitalPoint when a new post met a certain search query. For example, if I'm interested in learning how to make money using 7Search I could do a search for 7Search and then "Watch" that search and be alerted when new threads/replies about 7Search were posted. This would be a very helpful feature for research and keeping up to date with the latest information on topics you care about
If everything is presented to us, we would be watching only those Rather, dig deep to find out what you want by yourself. You will get across many new stuffs which could interest you more than what you were "really" wishing to watch for. Purely my personal opinion.