Björk’s Biophilia – “Virus” ($2): The first album app to deliver songs as in-app purchases, Björk’s Biophilia album represents a major expansion of the creative possibilities of the artist-released app. Having already wowed us with the first installment of the app, Björk released the next single this week — “Virus.” For an exclusive peak behind the scenes of how it was made, read our interviews with its main developer (part one; part two).

iClassics (free): To the uninitiated, classical is an outmoded form of music designed for old people and ads for their cars. Those with a firmer grasp of the genre know that stereotype is way, way off. There’s all sorts of richness and harmonic complexity in classical that you simply won’t find elsewhere, which makes it a more interesting option than you might think. As my father, the classical pianist, once put it: “Playing rock music is boring because it’s just the same thing over and over.” We wouldn’t go that far, because we dig repetition, but it’s true, to an extent. If you’re ready to ignore the stereotypes, iClassics has plenty to get you started: a radio station, timeline, and a nifty keyword-based tool for finding music to preview or buy. But even if you don’t bite on the paid downloads, this free  app is worthwhile for anyone who has ever wondered what is up with classical music.

VinylLove Pocket ($1): We were all over Color Monkey’s VinylLove iPad app when it launched, but never realized that the company also released this equivalent for the iPhone and iPod Touch. Recently updated to fix some annoying bugs, including one that was capable of crashing it at launch, this app lets you take a vinyl-like experience with you as you venture out into the world. The other major use case, which works better with the iPad version, is to prop it up next to your stereo during parties to let people pick tunes as if they were selecting records. You choose albums by browsing in crates, then drop the needle on the record to hear them play. The app even adds vinyl-like pops and crackles for that authentic analog vibe.

EGDR808 ($1):  The 808 drum machine changed the world — yes, really. Released in the early ’80s, this magical machine propelled hip hop past the sample, and was instrumental (doh) in dance music too. Although it wasn’t the first drum machine in the world, it was the first one lots of budding producers could afford, at $1,000 — the equivalent of  $2,600 or so in today’s dollars. By comparison, this $1 iPad version is a downright bargain.

Say What?! (free): Here’s a new approach to the music videogame: Say What?! plays music from a number of popular and a few upcoming artists (extra songs available as in-app purchases), and asks you to parse the lyrics fast enough to choose the correct object as it scrolls across the screen. For example, if Jimi Hendrix’s “Purple Haze” were included, you’d get points for tapping the “sky” from the lyric “‘scuse me while I kiss the sky,” but not for tapping “this guy.” Leaderboards are posted on Facebook.

Loopy Tunes ($2) Did you know that if you expose a kid to music, they will be the number one genius in the entire world forever? Well, they won’t. You should probably be a little more skeptical of such claims in the future. However, the link between music and intelligence has been established in numerous studies showing that musical ability translates to reading and other skills. Loopy Tunes (ages 2-7) promises to help a tot you know craft tunes on an iPhone, iPod Touch, or, ideally, an iPad, by “building up tunes with samples.” Milk bottles filled to various levels, piano keys, and pre-done samples are all available for your lil’ Mozart Einstein Super Baby to take the world by storm.

Google Android

Caustic (free; pictured top right): This app delivers a bevvy of useful features for electronic music-makers, and has been picking up steam on the Android charts. Some have compared Caustic’s functionality to the seminal beatmaking application Reason — and with good, ahem, reason. Similarly to that desktop software, Caustic for Android packs an analog subsynth, two PCM synths, two 80′s style BassLine synths a la Roland TB-303, sampling drum machine, sequencer, and mixer desk. The app features demo samples for these instruments as well, with built-in filters and effects to tailor your sound. The fully-functional demo version has no time limit, and allows users to explore its range of features before committing to the pro version with an in-app purchase. Unfortunately, the free version doesn’t allow for saving, loading or exporting files, although you could always record them through the output.

G-Stomper – Drum Machine ($6): Optimized for live performance, and sporting a tablet-friendly layout, this pattern-based groovebox lets you program beats with 16 preset patterns (of up to 128 steps in length) using as many samples as your device’s memory can handle. You can also custom-program as many patterns as you like on a removable SD card, thanks to its support for App2Sd (nevermind, iPhone people, you wouldn’t understand). G-Stomper packs useful effects — compressor, phaser, chorus/flanger, delay, and reverb, six filter types, and two equalizers.

2Player Network Music Player (free; pictured right): 2Player allows listeners to control playback remotely on any Windows 7 computer, Xbox 360, or networked “Play To” compatible device –directly from their Android phone. The app can also play and download music from networked Windows machines and media servers — bonus! The developer lists compatibility with most UPNP and DLNA devices (media servers, televisions, set-top boxes, etc.), though the app isn’t officially certified for those standards.

MP3 Catcher ($1): You may have noticed while browsing the web on your Android device that while clicking a link to an MP3 allows for playback, the OS doesn’t offer a way to download them. For a buck, MP3 Catcher fixes that oversight by letting you download MP3s from URLs and email attachments alike. Simply click on the file you want to download, select the app from the Action menu, and the MP3s get saved to your download directory.

Web Apps

eMusic Radio Beta (free to subscribers): eMusic subscribers in the U.S. will be happy to hear about its latest feature addition, which sets a course for music discovery in the form of an internet radio service, aptly named eMusic Radio. Radio is available for free to current eMusic members with comparable limitations to popular streaming services (i.e. 10 hours of listening per 30-day billing cycle, non-interactive, etc.) and offers collections of songs handpicked by eMusic staff with the help of tools provided by The Echo Nest (publisher of Evolver.fm). Updates to the service are sure to come, and word on the street from an eMusic spokesman suggests that purchasing options may be on their way soon.

Aupeo (free): Okay, this one isn’t a classic web app; it’s actually more of an internet app (yes, there is a difference). This streaming internet radio service brings over 120 genre stations, thousands of artist stations, and an intriguing Mood Tuner to your networked Onkyo home theater receiver. Onkyo owners can sign up for the Basic service free of charge, or upgrade to premium for higher quality, ad-free music at around $5 (or 5 euros) a month. (Onkyo has had its digital act together for about a decade, and also offers Spotify-capable receivers.)