Bibleworks, Accordance, Logos, and other Bible software (my only experience is with Bibleworks) offer unmatched functionality and ease-of-use, but are relatively expensive and are tied to certain operating systems. There are alternatives, two of which offer a similar suite of basic features.
The Resurgence Greek Project
The Resurgence Greek Project (RGP) is a quick, easy to use, and full-featured source for reading the NT. RGP offers simple searching, flash card generation, vocab lists, and other handy features. It provides the morphology and definition of words on rollover (which is very convenient). The major disadvantage is that it does not use the USB/NA Greek text. Instead, it uses Tischendorf’s 8th edition by default, and provides options for using Codex Sinaiticus, both of which are in the public domain. This is not a major problem, and it is understandable given the free nature of the service, and Perseus does provide some (pretty basic) text-critical analysis.
The text is Unicode, so you should have no problem in copying and pasting.
The RGP’s search features are pretty limited, but you can search for words by inflected form or by lexical form, and it also provides you with some statistical analysis.
Another great feature is the extensive flashcard modules. In addition to standard vocabulary lists, the RGP has the ability to create a vocabulary list based upon any selection of text. You can generate vocab cards for the book of James, for example, or all words in Romans that occur 15 times or less. This is a really great feature for studying.
The major disadvantage is the lack of other Greek texts, particularly those relevant to NT backgrounds. Also, the only available lexicons are Liddell Scott and Thayer’s, and while Liddell Scott is fine (if a little inconvenient, see below), Thayer’s has too many deficiencies to be reliable.
The Perseus Project
The Perseus Project is much more ambitious. It provides the entire NT (find that here), but in addition includes almost every Ancient Greek work available to us, from Euripedes, to Josephus’s Antiquities, to the early church fathers, and all in either Greek or English (and some other languages). You can browse their collection of Ancient Greek texts here, and they have other collections available as well.
Like Zhubert.com, the Perseus Project provides morphological analysis and definition, though this information is not displayed by rollover. Instead, a pop-up window provides the information whenever you click on the word. Also, the default lexicon is the Liddell Scout (Middle Liddell), which is a great lexicon, but not tailored to NT use like BDAG. You can find NT/Koine definitions in Middle Liddell, of course, but they are sometimes buried.
The search features are quite impressive. You can search by inflected form or by lemma, but the real advantage here is the ability to see how a word is used in other Greek texts. Since Perseus includes so many Greek works, you can search across a wide range of boundaries. (This can be a disadvantage, however, if not united with a little linguistic common since; Herodotus’s λογος is not the same as that of the NT).
The other major advantage to the Perseus Project is that it is completely Open Source. You can download the whole project, from the software to the texts (they are all in the public domain), and run it from your own computer (get the software here, and the texts here). Doing so will set you back a Gig or two, but it might be worth it, because one major disadvantage of their web site is its general slugishness (demand seems to consistently outweigh their bandwidth).
Conclusions
For basic reading of the NT in Greek I heartily recommend The Resurgence Greek Project. Its the easiest to use, has the most features relevant to seminary students, and is quick and responsive. If you want more extensive search features, or would like to read other Greek texts (such as those by the Church Fathers, or Greek 2nd Temple Literature), then check out the Perseus Project.
