Don't panic: Technical problems, emergencies and unexpected issues are rare but it can be beneficial to be prepared to deal with and even capitalize on them.
"Man doesn't plan to fail, he simply fails to plan."
Dealing with technical emergencies and other issues can be exciting, (where exciting is a rather ambiguous term). A good way to plan for problems is to ask the rhetorical question you'll ask when in the middle of an emergency: "What else could possibly go wrong?" I promise it can be fun and productive by using the right mixture of silliness and seriousness. Pick your favorite cynic and trudge 63,360 inches in his shoes. Do it now or he will be singing "I told you so" later!
In planning for emergencies it is necessary to weigh the cost/inconvenience of the risk against the cost/inconvenience of the failure.
"Hope for the best, plan for the worst."
The first step in weighing these items is to identify what is critically important to your cause and what are the potential failure points you are dependent upon.
Obviously your site is hosted on a server and you most likely are entrusting someone else to have it backed up with failover options if anything goes wrong. Do you know what the user experience and recovery will be like if something were to fail? What kind of error messages could be displayed for various situations? Please resist the urge to bring back one of those under construction animated GIFs from the early 90's! I know they're cool. You know they're cool. I predict a "retro internet" movement within 10 years that will bring them back along with flashing italics and marquee scrolling text! Back to seriousness... After a problem occurs, how will damage control be assessed and handled and most importantly, by who?
For collecting donations online, it may be worthwhile to have a backup method of collection. This can include a second host/server, payment processor and even pointing donors to an offline donation method if needed. I have seen several offline donation methods set up including pointing to a form, phone number or email address to either continue collecting donations or gather phone numbers or email addresses to be alerted later when it is possible to donate once again. For large donation campaigns, existing or emergency call centers can be utilized to continue accepting donations if set up in advance.
For email and advocacy action alert mishaps the most common recovery method is a mea culpa. Everyone gets to do it once: send an email either to the wrong audience or with broken links or some other mistake that reminds you both how small and large the internet is. I have seen some accidents resolved with web trickery including rerouting bad links or using meta refreshes to push the user from the bad link to the correct one. With broken links in an email, these fixes need to be very fast because, in general, the majority of the audience will view the email and take any action within the first few hours of receiving it.
"If you want to survive out here, you've got to know where your towel is."
The final step in preparing for emergencies is knowing the escalation path. You will likely need to know who in your organization will need to take action or be alerted. Also make sure you know the escalation process and procedure for escalating high priority problems.
"It wasn't raining when Noah built the ark."
It ain't all bad. A great way to make planning for emergencies fun is to also include strategies for turning a potential problem, emergency, or sudden opportunity into a good thing. For instance, you might see a much greater than anticipated response to a campaign that overwhelms your system. As soon as the system is stabilized reach out again to those who tried to donate or take action, thank them, apologize and let them know that the response has been so incredible it overwhelmed the system!
I was forced to watch at least one episode of American Idol last year because of the "Idol Gives Back" program. In general it was a great success but I hope to be your favorite cynic, I saw it as a missed opportunity. During the window of collecting donations the server performance was atrocious and the conclusion was "look how successful this was, the server was killed." There was a big opportunity there to say the demand was so great we have come back for an encore. Don't even get me started on the lack of Fox Network's understanding of eCRM. They made sure these were one time donations and did not make it easy for the non-profits benefiting to continue the relationship with the donors; few saw usable housefile increases.
On a similar note, be prepared for potential events, news items and opportunities that could require quick, emergency-like response to capitalize on. While strategizing on handling bad emergencies, take time to focus on potential good ones.
My last tidbit of disaster preparedness is this: Always have a hidden stash of chocolate. That's what my mama always said.