VME, introduced back in the 1980's is still very useful. The big installation base and many vendors gives a rich flavor of boards available.
In mid 1980’s few companies made the first agreement on VME standard. Shlomo Pri-tal at Motorola was leading the standardization of VMEbus. In the beginning Motorola 68000 family was the leading choice of cpu. Power PC had a big era and are still in use, now days Intel has the total market, even though ARM processors makes small steps to compete.
Due to being the choice for military market in decades there are a huge installation base round the globe. We still see upgrades of those systems as a market for new VME boards. Companies like Kontron and Concurrent Technologies have road maps for new boards.