From technical developments to projects like Digicash (1989), Cybercash (1994), E-gold (1996), HashCash (1997), Bit-Gold (1998), B-Money (1998), and BitTorrent (2001).
Those prehistoric coins laid foundations for more developments and a first successful digital currency, Bitcoin, with its genesis block mined in 3 January 2009.
I think that satoshi did really got his inspiration and based Bitcoin from most of these innovation of early invention of digicash. AFAIK, it was David Chaum's work for the digicash but it didn't nourished on 1998 and filed for bankruptcy. It's bad that it didn't got so much attention because that was the start of internet.
But there is a reason why it didn't became popular and so people have looked for Bitcoin when satoshi has launched it and this is the electronic money that have became successful and is now followed by a bunch of other cryptos.