Enca detects the encoding of text files, on the basis of knowledge of their language. It can also convert them to other encodings, allowing you to recode files without knowing their current encoding. It supports most of Central and East European languages, and a few Unicode variants, independently on language.
GNU Source-highlight produces a document with syntax highlighting when given a source file. It handles many languages, e.g., Java, C/C++, Prolog, Perl, PHP3, Python, Flex, HTML, and other formats, e.g., ChangeLog and log files, as source languages and HTML, XHTML, DocBook, ANSI color escapes, LaTeX, and Texinfo as output formats. Input and output formats can be specified with a regular expression-oriented syntax.
glark offers grep-like searching of text files, with very powerful, complex regular expressions (e.g., "/foo\w+/ and /bar[^\d]*baz$/ within 4 lines of each other"). It also highlights the matches, displays context (preceding and succeeding lines), does case-insensitive matches, and automatic exclusion of non-text files. It supports most options from the GNU version of grep.