You can use Safari 3.x to open Text files (they must have .rtf or .txt extensions), and then use Safari's Find feature to locate what you're looking for in the file. The advantage is that you get Safari's wonderful new 'find' UI instead of just plain old search results or filtered text.
In context, This is how I use it. There are periods of time when I do a lot of searching through log files. In doing so, I'm often looking for a particular phrase, and I also need to see the log data around that time period. Using Console just doesn't cut it for me, because when I put the search term in, Console blocks out all other data in the file. Opening the log file in TextEdit will allow me to highlight each hit individually, which is better, but still not perfect.
When I use Safari, however, it highlights all of the hits, and grays-out the other text. This allows me to quickly find associations between the search phrase and other things happening at that time. Of course, as mentioned, I do have to get the data into a .txt or .rtf file to do this, but hopefully, Safari will support other plain text extensions in the future. (Right now, if you try to drop a .log file on Safari, it will show you where it is in the Finder.)
Mac OS X Hints
http://hints.macworld.com/article.php?story=20080505101506466