UPDATE: New download link! Fully updated and now with Mediafire!
I'm crossposting this from the Something Awful forums, because it'll probably help somebody:
HoMM5: Tribes of The East content pack. Includes everything from the previous two releases, plus a genuinely exceptional fan-patch.
Got HoMM5: ToTE in the Steam sale? If not, get it from Steam here. It's still pretty cheap. Then unzip the content pack to your game directory. Just dump all the stuff in there - don't worry, it won't overwrite anything. Read the readme file if needs be, but I highly recommend you run the new EXE file (H5_AIadv_31f.exe) instead of the default HOMM5.exe. Just create a new shortcut for yourself and enjoy.
What is this pack? Well, it includes all the content from the previous two HoMM5 releases, and the very latest fan-patch release which fixes bugs, optimizes things a ton (so your CPU won't weep on larger maps - the original release could bring even godlike PCs to their knees), and makes enemy AI a bit cleverer in general and more customizable. One key thing is that the earlier campaigns now take advantage of the new features added in Tribes of The East such as caravans, which makes managing large empires infinitely less tedious and frustrating.
It adds up to a ridiculously huge and very polished game. 13 campaigns, 19 standalone scenarios, and a boatload of multiplayer maps that can be played against bots as well. There's a random map generator, a mission editor, and plenty of community-made maps and scenarios out there too. Game owns. A lot. Totally worth the money, even with HoMM6 on the horizon.
And just to reiterate, you ONLY need to buy Tribes of The East. Not any of the previous games. The campaign ports were done with Ubisofts blessings, and I provide links to the appropriate pages in the readme. They basically let the community do this because the expansions were standalone releases, so they abandoned support for earlier games before long.