well i guess it all depends on the kind of business being run. while ASP is suitable for small businesses, J2EE is probably the way to go when requirements get more dynamic and large scale. some people have mentioned Tomcat and MySQL with J2EE, but then I believe Websphere Application server is a lot better for enterprise solutions in terms of deployment speed, security and what not. i also think oracle/ms sql server are better options as far as back-end development is concerned. however, i haven't really had a chance to work with MySQL 5 yet, so can't comment much on that.
.NET i guess is still a prospect, but is handy if you're looking at a career at MSoft
my personal favourite is J2EE for, as bharat mentioned, its ability to make space for new things. not sure if anyone mentioned SAP here - it provides a lot more efficient means of handling data in the back end than most database systems, and this is also somewhere that Java comes in handy.