Online to-do list

[edg]

I'm looking for an online to-do list - something simple but powerful, like del.icio.us but for "action items" instead of links. There are five major features that I want:

speed of access - I want to be able to pop open a client and modify my list - whether it's adding a new entry, modding an existing entry, or deleting an outdated entry. (I also want to be able to mark an entry as "completed" without deleting it, but that's less important.)

keywords - I want to be able to assign keywords to an entry, so that when I'm looking at my list I can sort or filter by keyword: "work", "writing", "computers", etc.

access levels - I want the same kinds of access levels that LJ grants to posts: Anybody, All Friends, Some Friends, Private.

distribution of access - I want to be able to access my to-do list from anywhere, and modify it anywhere I have a client - but I also want to be able to make modifications offline with the client, and then upload them when I connect to the net again.

cost - I want something low-cost or free.

The LiveJournal To-Do List is almost what I want, but it lacks a few features (a non-web client, for one thing), and I just don't like the interface. Any thoughts?