According to this news story, the New Zealand government spends somewhere between 225 and 600 million $NZ annually on supporting the Māori language.
I don't know how much of this money is spent on providing publicly available online learning resources, but I'm guessing that the answer is either not very much, or if they have spent a lot of money on online resources, then they don't have much to show for it.
It would be good if the government did spend some money on providing online resources, because that would be an efficient way to make Māori language resources available to all New Zealanders, whatever their level of interest in the language might be.
The Government should also spend some money on making it as easy as possible for existing native Māori speakers to create online resources themselves, which could be something as simple as a central location for "blogging" in Māori, on whatever subject any contributor wants to write about, with features for adding English translations (added by writers themselves, or with the assistance of other collaborators).
The cost of creating and maintaining such online resources would probably be a tiny fraction of the numbers mentioned above.
The Māori language has something close to phonetic spelling. This implies that large amounts of vocabulary can be learned by an enthusiastic learner purely from written material.
The highest level of phoneticity occurs when macrons are used to indicate lengthened vowels.
Most newer online materials have macrons included, and it is easy to include macros in any content which is encoded in a Unicode-based character encoding (i.e. usually UTF-8).
A lot of older materials do not have macrons included, which makes them less useful as a learning resource.
The following is a list of all current online Māori Language resources that I have been able to find. Some of them are government-funded, either directly or indirectly. Some of them include content that is public domain, or freely licensed, for example with a Creative Commons licence.Māori Dictionary Online
This is an online version of Te Aka Māori-English, English-Māori Dictionary and Index by John C Moorfield. It lets you search for any Māori or English word, and it seems to work reasonably well.Ngata Dictionary
Another online dictionary. Unfortunately the search implementation of this dictionary is rather poor.
For example, searching for "ata" returns all entries that contain the characters "ata" in the result, with entries listed in order of English headword. So the first result is "abdicate", which is a translation of "whakataka", which happens to contain the characters "ata", but which has nothing at all to do with the meaning of "ata".
Also, searching for "mano" returns "creed", which appears to be a spurious match between lines in the Māori and English versions of the New Zealand national anthem, i.e. "Ōna mano tāngata kiri whero, kiri mā" and "Men of every creed and race gather here before Thy face". But actually, "mano" means "multitude", which corresponds roughly to a free translation of "man of every creed" as "all people" (i.e. "all the many people").
So, in summary, this dictionary is not a very useful online resource.A Dictionary of the Maori Language
This is an online version of the 6th edition of A Dictionary of the Maori Language by Herbert W. Williams, which is included in the New Zealand Electronic Text Collection.
There is no search interface provide to the dictionary, so if you want to find a word, you have to navigate to the specific page for words starting with that letter, and search within that browser page.
However, the content of the dictionary is provided under a New Zealand Creative Commons Attribution Share-Alike License. Furthermore, inspection of the web page source shows that the HTML markup is well-structured, making it easy to write software to parse the dictionary contents and re-structure it to support alternative interfaces.New Zealand Electronic Text Collection
There are other parallel Māori/English texts in the NZETC, although it is not entirely obvious how to find them all – the best option seems to be "Advanced Search", "My search terms are in Māori", "Māori-English / English-Māori parallel texts only", and search for some specific Māori word. However, if a very common Māori is supplied, then large numbers of results are returned, and some of them do not appear to be actual parallel texts.Kupu o te Rā
The name of this website means "Word of the Day". But, if you can't wait a day for each new word, you can read about them all directly on the website, which also contains a basic grammar of Māori.Kōrero Māori
This website from the Māori Language Commission contains a small number of learning resources.Ko te Paipera Tapu
Ko te Paipera Tapu is the New Zealand Māori Bible. This was published in 1868. Unfortunately the 1868 edition is not macronized.
The newer "Reformatted" Paipera Tapu is macronized, but it is not freely available online.
At BibleGateway.com you can to read the "Māori Bible" in parallel with an English version.
BibleGateway.com describes their version of the Māori bible as "Public Domain", and does not give any further details about the provenance of the text.
The Internet Archive version is shown as being sourced from Brigham Young University Hawaii. I presume that BYU Hawaii has scanned an original or facsimile edition, and that this has then been subject to OCR and possible manual correction of scanned text. (And presumably the BibleGateway.com version is derived from that text, because, where else would they have got it from?)
There are various non-online resources that can be found online, i.e. commercial books and CDs that one can buy (like the "Reformatted" Paipera Tapu), and I will not list them all there.
When one considers how much money the New Zealand government is spending on the Māori language, and compare that to how much money the publishers of commercial Māori content can ever hope to make from selling their content, it would actually make sense for the govenment to buy out all online rights for all existing good quality commercial Māori language learning content, and make all that content freely available online to all New Zealanders.
(And imagine what that technology could do if it was combined with translated content supplied by an army of fluent Māori speakers.)