I am extremely frugal when it comes to buying music and I will almost always wait for a deep discount before buying, so I just love it when one of my favorite bands offers free authorized music downloads!
The Grateful Dead archive site has run a promotion called 30 Days of Dead for many years; one month during which fans can download a 320Kbps MP3 daily of an unreleased and unique Grateful Dead track from the vault, selected by GD archivist and producer David Lemieux. If ya miss a day, you have all month to download the previous days' featured MP3's.
I have used this promotion to fill out my Grateful Dead collection and I really have enjoyed getting to listen to these gems that were mostly performed before I was born! I think it's fantastic that the GD community is just as supportive and enthusiastic about the band as ever. The Grateful Dead were a truly unique style and sound experience and, for me, they defined a decade and lifestyle I wasn't even around to enjoy.
If you are up on your GD history, you can even enter the accompanying contest each day and win a 2015 Grateful Dead calendar that features that awesome & iconic GD art style.