coinbase.com. Link your bank account and then you can buy them with a single click. Same way you get money onto paypal.
If you wanted to be really paranoid, you could set up a checking account just for stuff like bitcoin, and only load small amount of money into it right before making purchases.
But those are all anyone needs in order to withdraw the entire contents of your account, and they're being stored on someone's presumably-poorly-secured server. At least with paper checks they're, well, paper and are likely physically given to the bank for processing.
If you wanted to be really paranoid, you could set up a checking account just for stuff like bitcoin, and only load small amount of money into it right before making purchases.
My credit card account comes with an online service to generate one-time-use card numbers, for buying things from companies you don't exactly trust. So this suggestion is perhaps not so overly paranoid.
Donald Knuth (author of The Art of Computer Programming) no longer writes personal checks.
You write a cheque to X. X hands it to their bank A. A asks your bank B for the amount on the cheque. B asks A for the cheque to check its valid. B sends money to A. Done. Which is why I thought they take days to be processed.
Since the writing of a Knuth article, checks have become less risky, but they're still more risky than credit cards. [1]
So like I said, don't give your banking info out to just anyone. There's still risk involved. Whether or not you find Coinbase overly risky is up to your own utility curve.
[1] Knuth cites an article [http://perimetergrid.com/wp/2008/01/01/checks-the-most-dange...] which has since been updated [http://perimetergrid.com/wp/2008/01/01/checks-the-most-dange...]