If you were one of those people excited to hear that Apple was going to release a Yosemite public beta and you enjoy finding the gaps and the rough edges in software that's not quite ready for primetime, I've got a couple of suggestions for you.
Let's start with your Mac. Here we have the public beta of BusyMac's BusyContacts, which is from the same folks who make BusyCal. Lots of people have replaced the default iCal/Calendar app on their Macs because they've come up against a limitation of some kind, and BusyCal helps get around most of them.
This same issue with contacts is what prompted the BusyMac folks to develop BusyContacts. At Macworld 2014 I asked John Chaffee of BusyMac if they were ever going to do the same for contacts as they did for calendars and he told me about BusyContacts. I can neither confirm nor deny that I hugged him just for the possibility this could be a real app. You can enter your email address on the BusyContacts page to get on the beta list.
At an event (say a wedding or a party), you set up an iOS device (for example, your iPad) as "host." Then using PartySnapper, your guests can take photos at the party and send them to your device, where they get displayed on a larger screen (via cable or AirPlay). Now your guests can see the party while they're still there, and your iPad stores a local copy of each picture, so now you don't have to worry about tracking down all those pictures later.
Boinx has not only built a beta version of PartySnapper, but it is offering you the chance to test it out as part of a contest. Join the beta on the PartySnapper page, and after you host a party and fill out a questionnaire, you're entered to win an iPad Air 2 or a PartySnapper beer stein.
All the usual disclaimers apply here. Beta software can crash hard, or eat your data, or drink the last of the milk and put the empty carton back in the fridge, there's no telling. That's what beta means; it appears to have basic functionality but beyond that is anybody's guess, which is why it's called a beta test. Working out the bugs is super fun for some people. Others gladly trade being on the cutting edge for stable software. If you're interested, here are a couple of projects that could use your input. If not, here's a couple of nifty apps you can watch for in the future!