You could look at XSite Pro for website and content management - but it will only ever 'create a website', not necessarily a business.

Speaking of which, your website doesn't look all that big at the moment and your Alexa ranking suggests you have plenty of room for more traffic. Do you plan on growing your website - in which case WorldSubmitter from SBI will be invaluable in ensuring your content is regularly indexed and ranked.

** On the original question, what would happen if SiteSell went under. Unlikely, since SiteSellInc.com reports that profits are rising and the company is growing at about 35% year on year - but hypothetically..

I reckon that some of the filthy rich SBIers would dig deep and invest in rebuilding the company. Some of the software (which is probably patented) is worth a serious amount (Brainstorm It V3 could be sold individually for several hundred dollars EASILY) which could lend itself to being broken up - but then there's 40,000 SBIers who all have a vested interest. Perhaps SiteSell would become a co-operative?