Are you on Twitter, Sarah? There's the #plankaday challenge where you tweet your time. My best so far has been 2 min 30 seconds of the normal plank, but when I started getting bored of it one of my friends challenged me to do 30 seconds plank, 10 push ups as many times as possible, so far my best has been total of 3 minutes plank and 50 push ups (collapsed after the last 30 secs plank
), might have to try doing side planks in there somewhere.