Just how much CPU/RAM would I have to host 5 Ruby on Rails 3 programs?

I'm speaking about programs that won't have more than 300 hits daily each.

Measuring only a couple of hits each minute, despite permitting for optimum hrs and bursts.

It's difficult that i can make a reasonably new machine that will have issues with that.

But to reply to your question, it is dependent a little which web server you select but about 300 Megabytes / Rails server is really a beginning point for planning for a large application rollout. Because you will not be requiring plenty of synchronised transactions, a few threads must do and for that reason an entirely random 2GB machine ought to be ample.

I wouldn't really bother implementing a server without a minimum of 8 or 16 GB, though, even when not immediately needed. Because of the additional fees involved, a small budget allocation for memory should lead to a lot more than your scenario needs.