I'm in a similar situation myself - 22, living at (my parent's) home, ~4k a month pre-taxes/deductions etc and ~20k in cash (though I struggle to hit even an 80% savings rate, nice work!). I just maxed out my Roth IRAs with VTSAX for 2013/2014 ($5,500 each, not $5,000!), and plopped the rest into a VTSMX fund (working on building it up to VTSAX). As mentioned above, the stock series on johncollins are excellent reads, and I highly recommend actually understanding why you're investing instead of just blindly following someone's advice - he should read them! It is really nice to think of investing as something fun instead of something scary!
Also I think the mad fientiest has an article concerning Roth IRA vs Traditional IRA and the traditional IRA seems to be the better choice, even when you're in fairly low tax brackets...I have to run but I'll try to link the article in a bit!
Cheers,
Griffin