is there some particular subject, source type in your mind?
i guess very few primer source are aviable online but
?SAM - ?slam Ara?t?rmalar? Merkezi has some great treasures (also good cataloges), journals and if you can read Ottoman Turkish (like 19th century provincial salnameler/yearbooks, many articles in Ottoman Turkish, and very good catalogues), also the Istanbul sharia court registers and the excellent secondary source, the Diyanet Vakfı İslam Ansiklopedisi (beating the Brill's Encyclopaedia of Islam)
and there are other academic journals or primer documents here and there on other sites too, but it really depends on what interests you in particular, some sources are published in other successor states too (for example there are some defters related to Hungary published in Hungarian on Hungarian archive and library internet sites, i guess the same is true in other countries...)
I guess you are also familiar with the Center of Ottoman Studies in Belgrade
but sadly these are still just a drop in the ocean, there are some defters and manuscripts i'm really interested in, but even if they are digitalized, they are only accessible on field if i would go to the relevant archives or libraries in Turkey.
i'm in it, sounds like a great idea (and our interests then sound quite similar, though unfortunetly i'm just an amateur history lover, but love to read for example Ottoman tereke defterleri/probate inventories and studies based on them ).
If everything can come then this is also a good collection of links of Ottoman Turkish resources, can be great for studying Ottoman Turkish
Unfortunately there weren't many primary sources on the early periods of the Ottomans - let alone online. Do you know Turkish? (If so Ottoman Turkish or Latinized Turkish or both?) I believe there were still documents in the Ottoman archives waiting for historians. The Ottoman Empire is a very big subject but we know very little about it. As for the Economical and social structure of the classical Ottomans, Halil Inalcik is the best I believe. But you have to pay for the knowledge. I think you can't really dive into primary sources in this particular subject because it was mainly based on Ottoman tahrir papers which requires quite an advanced level of Ottoman Turkish. - I mean many of that sources written in Cryptic language called Siyakat - protecting the information. Tulun do you know how to read it?
We have to rely on Inalcik's works - though I am generally quite positive about his works. Thanks god that tahrir papers wasn't used in the very early periods.
Anyway, here's some of my English sources on the early periods - online.
haha siyakat script, i wish to, but it is way too advanced level subject for me.
as far as i know still Lajos Fekete's Die Siyakat-Schrift in der Türkischen Finanzverwaltung is the most recommended book on it, and in Turkish these works:
Dündar Günday: Arşiv Belgelerinde Siyakat Yazısı Özellikleri ve Divan Rakamları
Salahaddin Elker: Divan Rakamları
Mahmud Yazır: Siyakat Yazısı
Said Öztürk: Osmanlı Arşiv Belgelerinde Siyakat Yazısı ve Tarihi Gelişimi
I have some of them (though Fekete's work not unfortunetly) but they are at the end of my reading lists, i would be satisfied to be familiar with the basics of Ottoman paleography and diplomatics so i've just read only a few introductionary books on that.
if general Ottoman history online, another classic, Hammer-Purgstall's monumental Geschichte des Osmanischen Reiches is also on archive.org (and some other works of him too) i believe (also translated to English?).
Also some sources that are online from the Hungarian Cultural Heritage Portal, unfortunetly they are in Hungarian (except some of them includes an introductory or summary in foreign langues), but maybe can be useful for Tsar since some of them also cover parts of present day Serbia (Vojvodina):
I had a professor at Uni (a primus inter pares at European level), and he told us about an old friends of his, just an "amateur" in the field. He said he avoids professional talks with him as he didn't like to look like a noob …
It's long time I learned Tulun is that kind of "amateur" !
Tulun thanks for all these links and sources. The ottoman defters are a treasure hope all of them been carefull edited and published.
There is a series of taxation defters regarding Peloponnese, which interests me the most, and various Ottomanologists (Greeks like George Liakopoulos and Turks like Levend Kayapinar) who do a great job and with great merits to continue.