GCal Time Peek

When using Google Calendar's week view, time labels (e.g., 08:00, 09:00) are only displayed on the left-hand side. When creating or editing appointments on the right side of the view, it can be difficult to determine exactly which time slot you're working with.

This extension shows a tooltip or inline block with the exact timespan when you hover your mouse over any timeslot in the calendar grid, making it much easier to schedule appointments accurately. There's also a third option showing crosshairs for the column and row.