I've used the GoLogic analyzers... the software is pretty intuitive,
it has protocol plugins for some of the common ones (I2C, UART
(RS232), SPI, etc.) and a plugin development kit for more esoteric
handlers. Unfortunately, the cheapest one is north of $1000, but I've
used them reliably for a few years. http://www.nci-usa.com . I've even
done some SD/MMC debugging with those, albeit without a protocol
handler. Largely it was used for NAND/OneNAND/etc. interface
debugging, which isn't super-high speed, but I've used it up to about
20MHz I think, though it supports up to 100 or so supposedly.
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