I’m not sure if I posted this, and it was removed, but…
Lifehacker and Gizmodo both link to free/cheap apps every day and round up the best of breed on a monthly and yearly basis. I got indispensable things like Dropbox, Evernote and Dragon Speaking, (centralized file storage, excellent note-taking, voice recognition) for free by looking there as well as a metronome, a carpenter’s bubble level and a bunch of really useful work-related reference material.
You can also go to the iTunes store and search the free section or search for what you want. The free stuff that satisfies the search will be listed separately
The National Film Board of Canada makes all of their content available for free. Bargain of the decade, that.
For specifically Jewish apps I’ve gott iTehillim, iSiddur, Jewish Music, Rambam’s commentary on the Mitzvos and a couple others. The Talmud app was a little bit too expensive, but I may get it later.
HiE, Pandora isn’t just for “goyish” music. If you tell it what you want it will very quickly give you what you’re looking for. My Early Music, Klezmer and Classical channels are frighteningly good at picking out exactly what I like and nothing else. That’s the whole point of the Music Genome Project. You train it, and it will learn. Similarly, if you know people who have music channels you like on last.fm you can listen to their collections and them alone.