Well kids, I hate to say it but:
a) Spend a little more time on your database designs. The more you think out your design, the fewer changes you'll need to make later.
b) Figure out how to actually make a RELATIONAL database, use primary keys, try to actually take advantage of all the features of the system.
c) Learn when to normalize and denormalize your tables.
d) You probably don't need to go to the database every single time your user makes a request, so try and be a tiny bit more clever about caching and database connections.
e) Oh, and last but not least... use a database that CAN SCALE, like Oracle or SQL Server. Yeah, I know, they cost money, but guess what? You get what you pay for. All the Fortune 50 are using Oracle and SQL Server in production, and they don't complain about how it's not scaling.
None of these issues seems to be a particularly good rationale for abandoning the RDBMS / ACID paradigm. I guarantee that nine times out of ten developers who complain about the limitations of RDBMS could solve all of their problems by following any of the advice above, and the NoSQL technologies will only matter for extremely specialized cases. Look at what you sacrifice when you go this route:
"No schemas: NoSQL databases lack SQL's pre-defined table schemas, which makes changing data models simpler, but also offers no protection against invalid or outdated values in records." Are you high?
"No, or limited, data joins: generally speaking there are no built-in methods for chaining requests together in the style of SQL joins. Data denormalization must happen at the application layer." Man, sucks to be an end user! Oh, and how does it "solve" the problem if you're just moving the work from one layer to another?
"Restricted query interfaces: SQL is a mature and powerful query language, and the APIs available for NoSQL systems are not always as flexible. But, there are new capabilities here as well, such as CouchDB's flexible map-reduced based views." Wow, who cares? I'd like to be able to do a GROUP BY and not be worried that it's not implemented properly
I really don't see it. I mean, what problem are these guys solving, really? They're trying to create this whole new way of handling data that isn't robust, instead of using tools that actually work, just because they cost money? That's fine if you're a billion dollar company like Google or Amazon, who probably don't actually care whether or not their NoSQL projects succeed, but why spend all this time and money chasing a solution that will probably take decades of development and tuning?