EVERY TIME I tried to start this column about the overwhelming amount of free-and-legal music online, it seemed like I was interrupted by another downloadable compilation that ended up in my RSS feed, Twitter and e-mail. I’m not talking single MP3s; I mean full-blown collections of songs. In three days I’ve downloaded more than 20 free-and-legal mixtapes, online-only collections, promo podcasts and concert recordings. The music spans hip-hop, metal, techno, punk, indie rock, noise and six volumes of Kraftwerk covers.

The idea behind most of these freebies is to introduce new listeners to a band and inspire consumers to purchase the group’s music. And if you want a band’s full album, or a specific song — of if you still like to own a physical object — then, of course, you’ll have to buy it. (We keep things legal here, Jesse James.)

But if you want to stay frugal (and lawful), you could overload your iPod every week with quality gratis goodies without spending a dime. Throw in free Internet radio services such as Pandora and Slacker, add compilable playlists on YouTube, as well as streaming sites such as Last.fm, Swift.fm, Blip.fm, Soundcloud and MySpace, and it’s debatable whether you need to spend any money on music. (Again, not even talking illegal downloads, Ned Kelly.)

Below is a massive list of links to downloads that have invaded my hard drive recently. The only problem is actually finding the time to listen to them.

» VA, “They Don’t Know Unless You Tell Them” compiles 15 unreleased tracks by artists associated with Flingco Sound System, a fantastic boutique label that specializes in dark ambiance. The set comes as either MP3 or WAV files and features an amazing digital booklet designed by the mysterious Arlington, Va.-based experimental-metal musician Wrnlrd. [ambient, noise, experimental]

» Nosaj, “XLR8R Podcast: L.A. Mix (11.19.09)” plus remixes of The xx and Drake. [electronica, psychedelic hip-hop]

» Paper Tiger, “20 MIN MIX #3” featuring the Doomtree collective (P.O.S., Dessa, etc.). [hip-hop]

» Nite Jewel, “Stones Throw Podcast 54” mix plus her “Am I Gonna Make It?” MP3 [outsider electronica & funk]

» Strictly Kev (aka DJ Food), “Kev’s Kraftwerk Kover Kollection 1-6” features 200 interpretations of songs by the German pioneers, featuring everybody from Trouble Funk to The Cure. [electronica, rock]

» 114 mixes made for Fact Magazine from the likes of Simian Mobile Disco, Lindstrom, Cold Cave, The Big Pink, Andrew Weatherall and many more. [electronica & techno mostly, with some rock, hip-hop, etc.]

» Bok Bok, “Jan. 2010 Mix” for the Lower End Spasm blog. [club-music bangers]

» Green Velvet, “URB.com” exclusive mix featuring 16 twitchy club grooves by this Chicago giant. [techno]

» Ray Elliott, “Marking Measures” mix via the great Ghostly International label by this modern Detroit-techno DJ. [electronica]

» Numerous hip-hop mixtapes from the Nah Right blog, featuring everybody from Diplo (“Free Gucci: Best of the Cold War Mixtapes“) to Furious Styles & DJ Dub (“Jay Electronica: Victory“). [hip-hop, electronica]

» Terre Thaemlitz, “RA. 188” podcast for the essential electronic music site Resident Advisor. Plus a whole archive of nearly 200 mixes. [house, electronica, experimental]

» The Black Dog, “04. Krautrock: Return To The Source – DJ Set/Mix” features 16 mind-buzzing cuts from the 1970s German experimental-rock scene, mixed by this long-running avant-electronica trio. The group has an even newer, more electronic-oriented mix available for Tsugi Magazine, too. [rock, experimental, electronica]

» Laotze Sun Hammer, “Men and Women Seek Happiness” mix featuring darkly meditative tracks from Fennesz, Johann Johannsson and more; the preceeding three volumes are also available. [ambient, experimental, electronica]

» Nudge, “EU Tour EP” courtesy the Kranky label. [ambient, experimental]

» VA, “Mississippi Records Tape Series, Vol. 35: Satan Is Real” mix that kicks off with the Louvin Brothers and then heads right down the black metal highway to hell with Darkthrone, Venom, Mayhem, etc. [metal]

» Title Fight, “Live on WCBD Radio” will give you a taste of this great rough-edged punk/pop band, which plays Rock and Roll Hotel on Jan. 15 with Four Year Strong. [punk, pop]

» VA, “Alter the Press! 2010.01” mix features 16 tracks from The Wonder Years, Tiger Please, etc. [punk, pop, emo]

» Blockhead, “Megamix” is a 30-minute blend of this Ninja Tune DJ’s new album, “The Music Scene.” (Note: You need not enter your e-mail addy; just click “download.) [instrumental hip-hop, turntablism]

» VA, “The Official Radar 2010 Mixtape” was compiled by NME magazine and features The Drums, Avett Brothers, Surfer Blood, Washed Out and other buzz bands. [rock, electronica]

» Of course, if all that’s not enough — and it’s never enough — Amazon offers 116 MP3 compilation albums for free download.

Images excerpted from Wrnlrd’s digital booklet design for Flingco Sound System’s “They Don’t Know Unless You Tell Them” comp.