UI design for time tracking

I'm trying to think an interface for a time-keeping system that will let users see "at a glance" how much time still needs to be completed.

This is complicated by the fact that there are no fixed hours - employees must work at least 6 hours on any given week day, and at the end of each month should have worked 7.5 hours for each week day that month. 7.5 hours either way can be carried over to next month. Employees can also take up to 1 morning and 1 afternoon per month 'flex' time. Time needs should be recorded by 10.15 the following day, but this rule is bent during busy times, and end of week and particularly end of month boundaries become more important.

So what's the most readable format to display the currently entered time and highlight approaching deadlines for uncompleted entries, while still giving a feeling for how far ahead/behind track the employee is (i.e. if you have a week to go that month and you're 8 hours ahead you could schedule a little extra duvet time).

My first take was a bar chart for each day with a red line at 6. But this doesn't give you any idea of how far ahead or behind you are for each day or month or whether you are close to missing a deadline...

bar chart (Please excuse the horrible mockup)

Maybe I'm trying to convey too much info in one place?

Here's a mockup of time recorded v.s. time required as suggested by Dickon Reed graph of time v.s. target

EDIT: this side works great for stuff like this. i'm going to kick some of these ideas around in the morning and hopefully get something posted back here.

Solution

Your first chart could be improved by showing the remaining time as shown below. The remaining time until the next weekly/montly deadline is divided evenly over the remaining days before the deadline. So the UI will answer to the question: "How many hours per day will I need to work to meet my deadline?" If the user wants to take one morning/afternoon off (or did I understand you incorrectly?), you should have a checkbox for that day, after checking which the estimates will be adjusted accordingly.

You should also show the exact time on top of every vertical bar, so that the user doesn't need to estimate it in his head (I was lazy and added them to only a couple of bars in the mockup). Also highlight the current day, for example in the below picture this was done by circling "Thursday" and using a bold font for the time that the user has been working today. You could also use some visual effect for today's vertical bar.

improved bar chart http://img11.imageshack.us/img11/6755/20090216203339em2.png

For your second chart you should also draw in the weekly or monthly deadlines, as horizontal bars. In some cases the second chart might be better, but in this case I would settle with the first chart (with my improvements), because it might better correspond to the users' mental model, and that way you can also visualize the daily minimum 6h some way.