Diogenes is a free program for searching and browsing databases of ancient texts, primarily in Latin and Greek, that are published by the Thesaurus Linguae Graecae and the Packard Humanities Institute. (The databases are not distributed with Diogenes and must be obtained separately.) Diogenes has a graphical user interface based on Firefox.
Diogenes includes Perseus morphological data and the LSJ and Lewis-Short dictionaries. Jump from text to dictionary, clicking on a word to get its definition; and jump from dictionary to text, clicking on a citation to view its context. You can also now do morphologically aware searches: search for all of the inflected forms of a given verb.
The goal of this software package is to provide a free, transparent and flexible interface to the classical databases on CD-Rom in the PHI format, which include the TLG, the PHI corpus of Latin texts up to AD 200, the Duke Documentary Papyri collection, and the PHI-sponsored corpora of ancient inscriptions.
Provided that you are not using an antique computer and you are not running a search that turns up millions of hits, Diogenes should run quite briskly.
For advanced users, you can search for regular expressions (patterns of text), and there is a command-line tool as well as the web interface.
By default, the web interface displays Greek as Unicode, but if you need compatibility with other encodings, such as WinGreek, GreekKeys, or LaTeX, you can output Greek in many of these different formats.
Diogenes might seem somehow difficult to use, but if you play with it a while you will find out that it is rather easy. Unfortunately, by using this or other TLG software, you will not be able to search new additions to the TLG database, which are now available only to registered users of the online TLG project.