Share the progress you're making on a goal/habit with one or more accountability partners.

Create a new tracker type with the ability to add checklists/milestones and break them into smaller steps.

I have a few tasks where I need to track time. For example playing the piano. I I have a goal of 2 hours a week, and at the moment all I can do it count by minutes then do math to figure out 120 means 2 hours. This get more unweildy when I have a goal of 15-20 for something. It would be nice to be able to set a goal as a unit of Time, then add as units of time.

Here are some popular sites that you could pull data from to update goal progress automatically:

Fitbit - steps, miles, sleep time, calories
MyFitnessPal - calories, nutritional information
Runkeeper - miles ran, other exercises
Toodledo - tasks completed

Now I am achieving my target of twice per week, I want to increase this to 3 times per week without the past weeks all changing as they failed to achieve the new target, even though I did achieve the target of 2 times per week as it was at the time of logging it.

Please make app :)

When circumstances do not allow me to perform task I would like to have it turned off temporarily. For example I am out of home and task is about cleaning up home.
Thanks to that I would not be troubled by reminders and it would not count to task statistics.

Add an option to start a timer for a Habit to make sure I did it long enough to count as done. For example, rather than marking "Clean House" as Done, I could set a countdown for 30 minutes to make sure I do it properly. Could apply to meditating, practicing an instrument, learning a language, focusing on deep work, etc.

Currently just track by day, week or month and at the end of each month it resets the count.

For example I had completed something 27 times in a row and at the start of November it reset to zero as its a new month. I want to view how many times I've done something since I began it

It would be nice to see a weekly view which would show the list of the habits scheduled on each day so I know if I can add more habits on that day or if I added too many habits in one day.

I would like to choose when my day starts, instead of the default 'at midnight'.
I'm a bit of a night owl, so I stay up late and tend to sleep in. This constantly makes it seem like I'm behind on my goals, even when I'm not.

Say your goal is to practice yoga on average 3 times per week. When you get 3/7ths of the way through your week, if you haven't logged a yoga session then you get a notification saying "you need to do some yoga in order to keep up!", but if you have already logged a yoga session then you don't get a notification. Essentially you can then focus on avoiding getting notifications by keeping ahead of your habits.

Check out Waterlogged for a simple example.

For goals that have a start date & start value and an end date & end value, show a dotted projected line and an actual line.

For instance, if my current weight is 160, and my goal weight is 140, show a dotted line showing my expected weight any any time to meet my goal, and my progress to date with a solid line to highlight variances.

Productivity coaches such as Jason Selk and others recommend creating a daily success log in which a person records what went well during the day, what can be improved upon, and an action that can be taken toward improvement. You can kind of set something like that up, but only by using notes and kludging it a bit. Being able to create free form questions as a template and recording brief answers would be awesome. It would be an excellent addition to the app.

When a habit is moved to the archive, we should be able to set a date the tracking is stopped.
I like the data I used to have about % of days I accomplished the habit, but as time passes and I am no longer logging it because it has been replaced and is in the archive, the data is diluted by months of inactivity that is factored into the percentage. By archiving the habit, I want to preserve that data for the active period, not lose it to time.

As a user, it would be helpful if I could track my goals in the units I would prefer. For instance, if could track the drink water goal in ounces of water drank instead of number of times per day.