Someone has designed a Fibre Channel Flash Storage device that offers 144 Gig of storage. The rack mount can take up to 4 devices. Now, at up to £800 per gig, they are not cheap. While they are currently very good for companies or organisations needing to store huge amounts of data (the Serious Fraud Office uses one to store all it's scanned documents for instance), it isn't practical for home use.
However, the technology is getting cheaper. While Gigabyte currently do a drive that uses standard Dimms and a battery back up to provide several gig of ultra fast storage, it isn't perfect. The battery will still go flat at some point.
http://www.theregister.co.uk/2006/10...r_hard_drives/