I've owned a TR-606/TB-303, 2 TR-808s and currently own a TR-8. I bought my first 808 in college in 1998 for 750 bucks. Being a broke college student I sold it to pay for school. After college I bought another TR-808 for 700 in 2003 and kept it for 2 years. I grew bored of the sound, and had taken a decent enough sample set of it to replace it for most uses. The second 808 I had I modded to extend the decay of the kick drum to the point of self oscillation. I also bought a new row of buttons for it. Lastly I added a midi-DIN sync box. I had considered adding a pitch pot on the kick drum but prices were rising to the point that I thought was an 808 bubble(a princely sum of 1600 dollars). Now I see tr-808s on ebay for 3000+ and kick myself.

For anyone interested, the TR-8 does a good job emulating the TR-808/909 for the most part. I find the 808 cymbal(and to a lesser degree the hi-hat) sound nowhere near as good as the original and far less adjustable. The snares don't quite have the snap I hear in my 808 samples. It should be noted though that there was quite a bit of variation from unit to unit in the TR-808. My first 808 had a nice long 2-3 second kick decay, while the second one I owned was about .5 seconds(which is why I did the mod) the hi hat and cymbals are a slightly different pitch as well.

I bought the 7x7-TR8 expansion and while somewhat useful(I like the 707 snare) the 707/727 sounds rarely get any use. The expansion did include some new takes on the 909 kick, snare and non specific clap and snap sounds. I really like to play with the new snap sounds, as it is a cool noise generator effect. I haven't seen any news around this, but it seems silly for them not to do a TR-606/DR-55 expansion pack for the TR-8. I would have bought that over the 7X7 expansion.

There is a TR-808 documentary coming out soon 808themovie.com that will have tons of artist interviews who made their name with the 808. This article did a decent job of naming music that really used an 808, as there was one a few months ago that suggested mostly 909 tracks or tracks that may have used 808 samples sporadically in them. I get a bit pedantic about that because to me, you aren't using an 808 if you loaded a drum sampler with 808 sounds. Beastie Boys licensed to ill is a great example of an album made mostly with an 808(but synced up with a sequential circuits drumtraks and possibly a linndrum on one or 2 tracks) By the late 80s, most rap was made on sp-12/1200s and akai MPCs.