If you have a sound chip on your server which is capable of disconnecting itself from the microphone socket on the back then you might be able to use low-order bits from that and a tool such as the audio entropy daemon or 'randomsound' (the latter is packaged in Debian) however I'd not recommend that as anything other than a stopgap until you can get something more effective.
Simtec expect to release their Entropy Key for around GBP42 delivered in the UK. (worldwide postage costs will obviously inflate that a bit).
Simtec expect to release their Entropy Key for around GBP42 delivered in the UK. (worldwide postage costs will obviously inflate that a bit).