I've been using c:geo to geocache, I chose it simply because it was a free app in Android market. I head something about the developer stepping down, and in researching this I see all this debate about the ToS and the ethics of a third-party application. Its interesting to see how viperous the discussion has turned, and even though I'm a total newbie, I still can't help but shake my head at my fellow newcomers leaping to defend this (as it turns out) unauthorized software.
GS's application is poor. The interface is subpar, the features are lacking, and at $10 it is one of the most expensive apps I've seen in the Market to date. Pass. I don't blame ANYONE for not wanting it. That said, if c:geo is against the rules here, the only proper response is to uninstall it and find something else (I just did so). If you can't accept that, how can you be trusted to have the integrity to follow the conventions of geocaching in general? Do you also take all the stuff out of caches you find and leave nothing? Do you find the cache then toss the container into the weeds instead of putting it back? This activity depends largely upon the honor of the participants, and in this honor system one cannot arbitrarily pick and choose which of the rules and tenants to adhere to and which "don't matter". Following the rules for this site is just as central to the activity as any of the other aspects where you are left to your own devices and trusted to do the right thing in a community spirit.
c:geo is cool, it works great, and it is a bargain at twice the price (FREE!). But it just isn't a part of the game. Finding that out is disappointing, sure, but so is finding out that someone stole a cache or kept a TB. Don't be "that guy", now that you know it is against the rules, reject it, don't defend it!
Here's the process I adopted to replace c:geo. It works just fine!
Step 0: Download and install "GPS Essentials", a free and fully featured GPS app for Android. GPS Essentials actually has some features that c:geo lacks, including a readout of your GPS accuracy, how many satellites you have locked in, your current lat/long, etc.
Step 1: Find your caches through the geocaching.com map interface, note the coordinates and hints on paper
Step 2: Start the GPS Essentials app, add each cache's details as a waypoint. Waypoints may have names and descriptions, so I usually enter the cache name and the hint
Step 3: Hunt! GPS Essentials has a Google Maps-based live map display that shows your waypoints. You can also specify a waypoint as your target, distance-to-target and direction-to-target are shown.
You, like myself, started using c:geo because it was free and easy. Now that we know it is against the rules, the honorable thing is to remove the application and find another way. Once I found c:geo, I stopped looking because it did what I want. The take-away from this thread is that you need to keep looking.