You're talking like a maintenance log type thing? I just use numbers on my mac, but you could easily download ($9 i think) numbers for your iphone or ipad. Just a simple spreadsheet. There aren't any apps that I know of for this.
"What, exactly, is the internet? Basically it is a global network exchanging digitized data in such a way that any computer, anywhere, that is equipped with a device called a 'modem', can make a noise like a duck choking on a kazoo." - Dave Barry