Ask HN: Best language and database for specific project

I have a very specific project in mind that I would like to do on my own. It's high time I learn a little bit of backend.

I have an iPhone app (already made) that requests an ad in two parts - an image, and text. We currently use OpenX to deliver our ads, but our needs are much more simple, and we'd like the control of rolling our own solution.

So, I would like to create a simple backend. Database that holds the image, text, link, mobile link, and advertiser info. Then some sort of script to pull and deliver that info to our iPhone app.

Also, I'd like a basic set of analytics: impressions, clicks, maybe geo, etc. should I build this in or integrate Google Analytics or go with something like MixPanel?

Some details about our expected performance. We currently have a 512Mb VPS (Linode). We have between 400,000-500,000 impressions each month. We would want to build something that could scale much larger.

I'm drawn to Ruby, but want to use the best and easiest setup for the project. Python? PHP? JavaScript? I don't know much about databases... MongoDB, MySQL, nosql?

As always, thank you for your responses and help.