I'm going to recommend AstroGrep which has a very similar layout to the Google Snippet view. It supports plain text files. It is based of the UNIX utility "grep" and is completely free to use. It also contains a numerous amount of options as well for searching.
AstroGrep is a Microsoft Windows grep utility. Grep is a UNIX command-line program which searches within files for keywords. AstroGrep supports regular expressions, versatile printing options, stores most recently used paths and has a "context" feature which is very nice for looking at source code.
Here's a screenshot of it in action:
