I really liked my Intrepid Systems "ValueCAN" USB adapter, since it could handle a fully loaded 1Mbps bus, but it died on me. This is the second one that died this way, so I'm not inclined to buy another. (The hardware is likely fine, but it can no longer get out of the PIC bootloader, as if it lost its programming.) Doesn't seem to be supported any more. The bundled software is pretty nice, and I wrote my own Linux library for it. If only they were cheaper.
I have an Acacetus CAN-uVCCM, which is a fine isolated RS-232 adapter with a versatile serial protocol. Its fatal flaw is that it maxes out at 57600bps RS-232, which is nearly useless on today's system. Still, if you set up the filters appropriately or just use it as a test sender, it works well.
I have a pretty old (2004) Lawicel CAN232 adapter. This one works reliably, and has the unique ability to run at 230kbps on the serial side. This is the one I'm using now, and the serial format is well-documented:
In combination with an FTDI USB-RS232 adapter that can do 230kbps, it works great.
I see that Lawicel now sells a CANUSB, which has an integrated USB chip for higher bitrates.
I have an Atmel ATDVK90CAN1 kit somewhere and a Proconx.com XNUT-105 CAN board for embedded stuff. If we can get some clarity on the SOC messages, I'd probably build a mobile display out of that.
So this is all old gear from 2003-2005. What are the cool kids using these days? I imagine there's an Arduino CAN variant by now?