I'm not an Apple guy, but I'll throw another vote in favor of Logten Pro. I tried several free logbooks, and nothing matches the ease of use or does exactly what it can do. Keeping track of currency and duty limits is effortless, and it's nice for keeping track of all your different flight categories. Also, generating a PDF of a Jeppeson style paper log that you can print out for interviews takes about two clicks. Other programs will do the job, but Logten just does it more efficiently.