The iPod and iTunes both have a "Shuffle by Album" feature that I'm pretty fond of, because some albums just work that well as a cohesive whole, and the songs are that much better when there in place besides their brothers and sisters. But this is where the "but" goes, because why would I have bothered to write that first sentence if there wasn't one?
"Shuffle by Album" is a very nice feature, but both the iPod's and iTunes' implementations of the feature have implementational problems. iTunes' problem isn't that big a deal; it's just a minor irritation. The only way to switch between "Shuffle by Album" and "Shuffle by Song" is by opening the preferences, going to "Advanced," and switching the little radio box there. As problematic as the weird three state behave of the repeat button already is (it switches between no repeat, all repeat, and 1-song repeat), I think they might as well just make the shuffle button be another three state button that just cycles between no shuffle, shuffle by song, and shuffle by album.
The iPod's problem with Shuffle by Album is much more significant, in my opinion: Just like iTunes, the iPod only shuffles the tracks or albums in the current context. The problem is, if you "Browse by Album" with the iPod to select what album you want to listen to, the context is just that single album, so when the album is over, the iPod doesn't have any other albums to shuffle to, so it stops playing (unless you have repeat all on). To get it to actually shuffle through albums, you have to browse by song and then select the first track of the album you want to listen to. When you have 8,000 songs on your iPod, this is a little problematic (to say the least). I suppose you could just click on any song of the album, and then hit back a few times until you get to the first track, but that kinda sucks. Unfortunately, I don't think there's any way to present a consistent interface and make the Shuffle by Album really work. The best solution might be to introduce another setting for "Repeat" in addition to "Off," "All," and "Songs." The new setting would jump into your entire song library after it finished playing the songs in the current context.
The work-around I've been using on the iPod for the Shuffle by Album problem is this: I add the albums I want to listen to to my On-the-go playlist, and then it's a much simpler matter to find the first song I want to listen to. The only real problem with this solution is there's a bug with the On-the-go playlist. Once you start playing a song from OTG, it caches the context the OTG playlist was in when you started playing. Because of this, even if you add more songs to OTG, they won't get added to the possible songs that will be selected by shuffle until you manually go and select a new song under OTG. This seems like an obvious holdover from when the playlists on the iPod couldn't actually change. Hopefully they'll fix it soon.
Oh, another possible way to solve the iPod's Shuffle by Album problem besides another "Repeat" setting is this: Add a "Browse" feature to every "playlist" you can get to, so that if you select "Browse -> Songs," there will be a be another "Browse" menu that will preserve the context of "all songs" (or whatever playlist you happen to be in), but will allow you to select an album. This would closely mirror the way iTunes Artist/Album browser works. This would show up under everything, including anything already under "Browse," and any playlist you're looking at, including the OTG playlist. The only real problem I see with this is that the number of "Browses" deep you are could get pretty confusing pretty quick. But this would solve other issues I've had with being able to navigate some of my larger playlists, or with wanting to find the first song of an album in one of my "by artist" playlists. I think this is a reasonable idea, but the particular interface presented needs little more thought than I've given it here.
iTunes feedback goes here, and iPod feedback goes here.