The OpenBSD Project (Foundation?) needs to pay a large electrical bill for their hosting location. I had mentioned this in a weekend BSD report just before the end of 2013, but the problem is still there and deserves a special mention. It’s possible to contribute directly, or to the I-assume-nonprofit-so-tax-deductible-for-many-people OpenBSD Foundation. You can set up a low but reoccurring Paypal payment for the Foundation, which would be probably unnoticeable for you but very helpful for the organization.
Even if you aren’t booting OpenBSD on anything, you’re using a technology that came out of that project – OpenSSH, pf, your dhcpclient, etc; or using 3rd-party software that received fixes from OpenBSD work. Putting dollars towards this software development is one of the more effective things you can do with your money to help open source.