You can include the Google Chart API-based clock, used in Google time oneboxes on search results, even without knowing the cryptic signature used. As an example, when you search for http://www.google.com/search?hl=en&q=time+in+berlin%2C+germany the top result reads "1:43 PM Tuesday (CET) – Time in Berlin, Germany" and shows a clock icon. The clock icon URL is

www.google.com/chart?chs=40x30&chc=localtime&
cht=cf&chd=s:Ns&sig=Xj0oRMbrvCU5gfWa2EG4KyHC8jI

You can't just remove the "sig" parameter, but you can remove both the "sig" parameter and the "chc" parameter... then you can include the clock, and also change the data type, like this:

http://blogoscoped.com/files/chart-clock-12-90.png
http://www.google.com/chart?chs=40x30&cht=cf&chd=t:12,90

Here the parameters are e.g.
chs=40x30&cht=cf&chd=t:12,90

The first value, 12, seems to be for the hour hand in the clock, and the second value, 90, for the minue hand. The minute hand seems to be based on 100, e.g. 90% shows the circle 90% done, but what is the hour hand number? E.g. "12" does not result in 12 o'clock. (Note the clock shows daylight as yellow and night as blue, I think.)

Some previous discussion by George R. and others: http://blogoscoped.com/forum/117581.html#id117905

[Thanks http://alacatialabs.com/2008/01/07/clocks-with-google-chart-api/!]

Interesting hack :)

I think that starts from -1 and can be filled in with decimals.