cDK.com

Can be purchased either assembled or kit from Seeed Studios.

I've received advice that having a dedicated/benchtop unit is handy because it instantly powers on and you don't need to worry about software configuration, and since I think there is something to be said for a dedicated device, I am researching which devices would meet my needs, and also trying to determine if any of the "pro" benchtop units, could potentially be picked up for cheap in the used market:

• HP/Agilent 167x series (1671D, 1670G, etc.)
• HP/Agilent 166x series (1664A, etc.)
• HP/Agilent 165xx mainframe series (16500, with 16550A, 16531A, etc. options cards)
  (HP Mainframe units have HP-IB interface, as well as TP-Ethernet so you can connect from a PC and control/monitor the system remotely over X-windows or transfer plots over FTP/NFS.) 
• Tektronix TLA 704 (what? runs embedded Windows 98? i wouldn't buy that!)
• Tektronix TLA 520
• Tektronix TLS 216 

I will be doing further research here to see what is available used, but still in the "hobbyist" price range.

Comments: The Circuitgear 101 has open-source software support, and supports all three platforms, so I might consider it even without having an open hardware design. And, SyscompDesign Supports the Open Instrumentation Project.

The speed is so slow!  2Mhz analog and 20MS/s digital won't meet my needs. :(

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Comments: I like seeing the 200MS/s sample rate on digital logic, but other than that, it's a closed-source proprietary device and only supports Windows, so I can't use it.

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Comments: Modular stacking approach means you can use up to 4 devices at once, but that adds up in cost if you need that.  Overall, supported by LGPL/GPL software and looks very portable if you need a 1-channel device.

Companion products from Elan include Function Generator, Clock Generator, and Pulse/Clock Counter.

Designed/sold in the UK, but can be purchased in the US through Synchrotech.

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Comments: The hardware looks nice, but the bandwidth and sample rates are a bit slow. (They do offer more capable units which are more expensive.)

They officially only support Windows, although there are some code samples on discovering and initializing the device from any operating system, if you wanted to develop your own Linux or Mac support  While it might be a fun and interesting project for me to develop the Linux drivers for these, I'm interested in having one work out of the box for now.

One thing that IS really cool about their existing application suite is the number of protocol decoders they have, including USB on the wire, but you have to run Windows to run their software suite.

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Comments: No oscilloscope, spectral analysis, or waveform generation function.  This one is multi-platform, but not open-source.

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Comments: No oscilloscope, spectral analysis, or waveform generation function.  This one is multi-platform, but not open-source.

Max samples/sec varies based on #pins sampled. 2 pins = 100MS/s, 16 pins = 12.5MS/s max.

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Comments: No generic multi-channel digital logic analysis, but more of a 2-wire CAN protocol type analyzer.  This little unit would be very flexible and useful in hacking on MIDI circuits, small arduino serial interface projects, etc. but not usable for tracing 8-bit data lines on micro-processors circuits.

Dangerous Prototypes makes the PCB, but the buyer purchases the components and assembles the unit. You could also purchase a pre-assembled Bus Pirate v3 unit from Seeed Studios.

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Comments: This one is definitely capable of multi-channel logic analysis.  It is the hardware that enables the SUMP software client to do the analysis.  The SUMP software is Java-based, and uses the RXTX library (host-device communications) for broad cross-platform support.

The Sniffer has external Trigger IN and also Trigger OUT to external devices.  I don't know yet how this could work with a digital storage oscilloscope, but presumably could be made to slave the scope to a set of logic.

Dangerous Prototypes makes the PCB, but the buyer purchases the components and assembles the unit. You could also purchase a unit pre-assembled (recommended) from Sparkfun (US), GadgetFactory (US), or Seeed Studios (China).