Question: I am looking for a visual tail tool that can monitor several local or remote log files.

Optional features that interest me: color highlight based on log error level, coloring for special words, filtering of messages and/or notifications on new activity.

Answer: 
Only for the sake of completeness it shall be said, that there is a tool for Mac OS X with highlighting on keywords and some other features.
It's called [Logtastic](http://www.logtastic.net)

I know, this is an old post, but maybe someone finds this useful?! :)
I was looking for something similar a few months back and discovered and excellent Linux appliance distribution called Security Onion: <https://security-onion-solutions.github.io/security-onion/> 

I pretty much ignore the IDS and packet capturing (for now) and just use it for log analysis. It was pretty simple to set up virtual box and then load the Security Onion image. Other than being a little RAM hungry it's a great way to get some pretty sophisticated log analysis from several really good open source packages that are already integrated in a read-to-use solution. Now that I have logging pretty much taken care of, I might start playing with some of the IDS features built into it - but that takes even more RAM...