Hello,
I have started to using free version of KLOK program, and considering buying a full version. Usability is one of the most valuables things for me, and that’s what I like about KLOK.
However a found are a few things that might improve joy while working with KLOK even more:
1) Duplicating calendar entries while dragging and holding Ctrl. This is common behavior in MS Office applications, Graphic editors and other software.

2) Data in the timesheets could be sorted either alphabeticaly, or according to project structure in KLOK.

3) In timesheets subtotals for the projects (at first level project level) could improve visibility of total hours spent on particular project. I think most of the users use first level project as a actual (billable) project, and sub-projects as a specific project activities, so having aggregated amount at the project level would show actual billable amount for this client.

Besides these small things I like using KLOK and find it very useful.