There were a few others out there but none of them were widely adopted until PCI.

As for AGP there has been multiple versions
AGP 1x
A 32-bit channel operating at 66 MHz resulting in a maximum data rate of 266 megabytes per second (MB/s), doubled from the 133 MB/s transfer rate of PCI bus 33 MHz / 32-bit; 3.3 V signaling.
AGP 2x
A 32-bit channel operating at 66 MHz double pumped to an effective 133 MHz resulting in a maximum data rate of 533 MB/s; signaling voltages the same as AGP 1x;
AGP 4x
A 32-bit channel operating at 66 MHz quad pumped to an effective 266 MHz resulting in a maximum data rate of 1066 MB/s (1 GB/s); 1.5 V signaling;
AGP 8x
A 32-bit channel operating at 66 MHz, strobing eight times per clock, delivering an effective 533 MHz resulting in a maximum data rate of 2133 MB/s (2 GB/s); 0.8 V signaling.

AGP Pro was more of an offshoot for graphics design and more power hungry cards. There was AGP Pro 1.5V, 3.3V and Pro universal slot. This standard is pretty much dead in the water since PCI Express is receiving so much acceptance.

The other one to mention is PCI-X this is NOT PCI Express, This is a older and totally seperate standard from PCIE. It is PCI-eXtended. Similar to how EISA was to ISA. Never did receive much acceptance since AGP was becoming the standard around 1998.

There are some good articles on Wikipedia at
http://en.wikipedia.org/wiki/List_of_device_bandwidths#Computer_buses
http://en.wikipedia.org/wiki/Industry_Standard_Architecture
http://en.wikipedia.org/wiki/VESA_Local_Bus
http://en.wikipedia.org/wiki/Extended_Industry_Standard_Architecture
http://en.wikipedia.org/wiki/Micro_Channel_architecture
http://en.wikipedia.org/wiki/Peripheral_Component_Interconnect
http://en.wikipedia.org/wiki/Accelerated_Graphics_Port
http://en.wikipedia.org/wiki/PCI-X
http://en.wikipedia.org/wiki/PCI_Express