so, 37signals sunset the free versions of Basecamp and Backpackit. Basecamp was a kickbutt project management / to-do list tool, especially for teams, and Backpackit let you set reminders for yourself and be emailed or SMSed when the to-dos came due, as opposed to clogging up your STD (sh!t-to-do) list.
i’m using Toodledo as a replacement for Basecamp and Wunderlist as a replacement for Backpack. Toodledo has a good iPhone app and website, and if you treat folders as projects, it’s easy to work on different projects, say grad school STDs or whatnot. Wunderlist emails you at a certain day and time. both are free.