The academy's Academy
But what they are really useful for (no offense meant!) is their Historical Dictionary. A historical dictionary aims to chart the development of individual words in a language throughout history, through fluctuations of meaning and nuance.
But, as Jacob Nachum Epstein put it, "our primary need is the text". To properly study language without getting caught in anachronisms, linguists must establish a dependable text. So the Academia, as it is called in the right circles, set out to produce such versions of every surviving Hebrew text. They decided that, for each unit of text, they would use only one manuscript, the best one available. This is an arguable choice, but a sensible one, since dealing with multiple textual witnesses would simply make this huge task huger.
To make a long story short, they produced a database of all Hebrew texts (minus the Bible) up to the end of the Geonic period. Each text is based on a manuscript. Every Hebrew word in these texts has been classified and cross-referenced. And all of this was made available on CD-ROM. That includes all of Sifrut Hazal, classic Rabbinic literature. Mishna, Tosefta, Bavli, Yerushalmi. And so on. Many of the piyutim, the ritual poems, are unavailable in print, other than on this database, which is called Ma'agarim.
According to their website, the CD is now available for the price of NIS 800. Bearing in mind that the interface on the database is as helpful as a clerk in a government office, it is still a good price.
The big news is that, at some point in the future, they are planning to launch a subscription service on the Internet, with access to the new version of Ma'agarim. This new version is supposed to have new resources, and a better interface. The rumour was it would cost NIS 100 a year, and would look like the Bar Ilan Responsa Project. I don't know whether that's true, but in any case it's something to look forward to.