I just let it drip dry in the garage. I'm a commuter in the upper Midwest, so I get my share of rain. I don't go out of my way to avoid rain unless there might be serious action such as hail, and I've been caught in storms where I literally pour water out of my shoes when I get home.
My summer and winter commuter bikes have internal gear hubs, which supposedly are more weather proof, but derailleur systems are pretty robust. In fact I think that bikes are a lot less delicate than folks tend to assume. I've gotten a bit of minor surface rust on chains and cogs, which doesn't really affect performance of the bike. Now if I wanted to keep it showroom clean, it would be a different matter, but none of my bikes are worth that kind of attention.