Well, things have changed a lot since the last time I looked into tape trading. Notably, the proliferation of inexpensive CD-R burners has made it so that people can trade CD-R media instead of DAT or cassette tapes. This has also made it easier for people to get into the community without having recording equipment because it's easier to find people who will help you build your library by doing what's known as a B&P. B&P stands for "Blanks and Postage" and how it works is some guy who doesn't have much (that would be me) asks someone else who has some good shows if they would burn a copy of the shows for him. The recipient of the B&P is responsible for everything except for the actual burning of the CD-Rs -- postage both ways, the blank CD-Rs, etc. That's a pretty high-level overview of the B&P process. More detailed information can be found at McNichol's Beginners B&P Instructions web page.
I think people are more willing to do B&Ps now because it's simply so easy to do in the age of high-speed CD-Rs. When you used to have to mess with cassettes, it was a pain. Now, it's a piece of cake. I'm very grateful for people who are willing to do B&Ps, because it is helping me grow my collection. I started out with nothing, now I've got several people who are burning some great shows for me. In the next few weeks, my mailbox should begin containing the fruits of my B&P legwork.
In addition to growing your music library via generous B&P offers, you can grow your library by downloading music from the internet -- a lot of shows are just floating out there, ready to easily get. A great place to get them is at the Internet Archive. I've been downloading the likes of Glen Phillips with Nickel Creek, Yonder Mountain String Band, and Little Feat. Typically, the files are compressed in a lossless medium (SHN and FLAC appear to be the popular ones), which is great -- the files are smaller than the uncompressed audio files, which makes for faster downloads/burns and the files are also documented with MD5 checksums, so you can be sure that you grabbed a reliable copy. I'm really impressed with the way all of these music fans are using the technology to make this happen.
A great place to find people to trade music with or people making B&P offers is etree, espeicially the mailing lists and the trader's database. Individual traders can easily create pages that list the shows they have and the shows they want. For example, I created a page to list a few of the shows that I've downloaded so far. As my library grows, I'll be working on organizing that page a bit better.
Between the downloading I've been doing and the generosity of several B&P offers, i expect to have a library of 10-15 shows in the next several weeks.
The bad news for me is that I don't yet own a CD burner. Yeah, I know. It's time to join the 21st century. I've been putting off getting one for almost a year now, but my new found passion for this hobby might push me over the edge to get one. In the mean time, if anyone has a (cheap or free) external (usb 1.1 and/or firewire) CD burner that works with Mac OS X (Finder and iTunes) and is capable of burning DAO, let me know.