If you went play framework w/ Scala it would be pretty hard to avoid learning some OO and you could also learn some functional stuff. You've got enough background to get over the initial hump, now start writing "interesting" stuff not just yet another CRUD app.
You seem to have a database sized hole... The hard part about databases isn't the syntax, or peculiarities of specific DBs, or even optimization tricks to make things faster, but design. What is normalization? Why/When would you want it? What tasks need a relational design, or not... Even if you never pivot into being a DBA it helps alot to at least minimally speak a DBAs language when you write a CRUD app talking to his DB.
Programming as in slinging code syntax stuff, or higher level design? Might want to crawl inside algorithms for awhile with Knuth and other books. Much like learning Algebra its not like you'll ever use it, its more to discipline the mind to figure out other complicated stuff. You should really google for and spend a lot of time at "project euler" if you're trying to learn higher level programming. Many of the PE problems aimed at turning you into a better mathematician can be hacked on brute force-ish to make you a better programmer. As a hint the first problem you're not "supposed to" brute force add those together, you're "supposed to" figure out the easy formula. But writing the brute force adder is none the less an interesting experience if you've never done it before in your language of choice. (edited to add, buy and read and "do" the entire "little schemer" series, or at least the first book)
I don't know if this would make you more employable, but in terms of extending your greater computer-ish knowledge you could do worse than some embedded stuff. Get an Arduino and some shields and some servos and some sensors and make it do something really well. You claimed to know a little bit of C so here's something fun to do with it.
You also seem to have an OS sized hole in your list of experience so some systems programming type experience might be interesting. Get a couple free machines (castoffs) and figure out how to use Puppet to make them jump thru hoops. Since you have a cluster, there's a lot of fun you can have learning how clustering/replication tech works and scales. Don't worry about using old junk computers, there's absolutely no difference between clustering on new big iron and on a free junkpile P3 other than the new stuff is faster. Make your own DB host and a bunch of front ends and see what happens. Maybe try a cluster of DB hosts and FEs talking to the DBs. Much like the DB thing you may never become a sysadmin but learning to speak their language will help even if you stick to webdev work.
You seem to have a database sized hole... The hard part about databases isn't the syntax, or peculiarities of specific DBs, or even optimization tricks to make things faster, but design. What is normalization? Why/When would you want it? What tasks need a relational design, or not... Even if you never pivot into being a DBA it helps alot to at least minimally speak a DBAs language when you write a CRUD app talking to his DB.
Programming as in slinging code syntax stuff, or higher level design? Might want to crawl inside algorithms for awhile with Knuth and other books. Much like learning Algebra its not like you'll ever use it, its more to discipline the mind to figure out other complicated stuff. You should really google for and spend a lot of time at "project euler" if you're trying to learn higher level programming. Many of the PE problems aimed at turning you into a better mathematician can be hacked on brute force-ish to make you a better programmer. As a hint the first problem you're not "supposed to" brute force add those together, you're "supposed to" figure out the easy formula. But writing the brute force adder is none the less an interesting experience if you've never done it before in your language of choice. (edited to add, buy and read and "do" the entire "little schemer" series, or at least the first book)
I don't know if this would make you more employable, but in terms of extending your greater computer-ish knowledge you could do worse than some embedded stuff. Get an Arduino and some shields and some servos and some sensors and make it do something really well. You claimed to know a little bit of C so here's something fun to do with it.
You also seem to have an OS sized hole in your list of experience so some systems programming type experience might be interesting. Get a couple free machines (castoffs) and figure out how to use Puppet to make them jump thru hoops. Since you have a cluster, there's a lot of fun you can have learning how clustering/replication tech works and scales. Don't worry about using old junk computers, there's absolutely no difference between clustering on new big iron and on a free junkpile P3 other than the new stuff is faster. Make your own DB host and a bunch of front ends and see what happens. Maybe try a cluster of DB hosts and FEs talking to the DBs. Much like the DB thing you may never become a sysadmin but learning to speak their language will help even if you stick to webdev work.