what are some good tag Cloud logic that you had come up with? like fontsize = factor * percentageOfOccurance ....
You'll need to set a minimum size, so maybe fontsize = minsize + factor * percentage.
You may want to limit the range of sizes; perhaps take the sqrt or log of percentage, but this depends on your distribution.
For another technique, have a look at this blog post from poeticcode on Tag Clouds Algorithms:
Next, in the linear interpolation, how do we set the min and max boundaries for the font size/color intensity? I notice that Amazon.com for example, is ranging it’s font sizes between 80% and 280%. So, the lowest tag in the cloud would get a font size of 80% and the highest tag 280%. I have decided to go with the following formula
150*(1.0+(1.5*m-maxm/2)/maxm)
This nicely gives a font size from 75% to 300% as the metric changes from a potential 0 to maxm.