Web/iOS/Android/Chrome: If Astrid's pending shutdown has you bummed, or you just want a syncing to-do app with solid recurring task options and collaboration tools, TickTick is a new kid on the block that's worth a look. It's built by the same folks behind GTasks, another tool we've mentioned.
The service is in beta, and the web interface is pretty sparse, but if you loved Astrid, you'll be familiar with the look and feel of TickTick. Plus, you get seamless syncing between the web app and its iOS app (the dev says an iPad-optimised version is on the way), Android app and Chrome extension.
Adding new to-dos is as easy as typing them, and you can set deadlines and set custom reminders for specific times of day. You can set the to-do to recur every day, week, month or year, complete with specific repeat days, so you can have a daily to-do repeat every five days, for example. You can even set when the to-do should stop recurring. Like any good to-do app, you can organise your items into lists to keep them separate, and get a daily or weekly view of everything you have coming up. You can add notes to individual to-dos, create lists with to-dos and subtasks beneath them, and share to-dos with other users.
The developer has "labs" features you can enable, like search or a calendar view, but some of them are limited to TickTick's $10 per year "pro" accounts, which don't really get you that much right now. However, as the service grows, it can either be a great way to try out new features or a way to nickel-and-dime people into upgrading. You can check out the plans here/a> and read more about its features here.