Here is my method of generating the character groups.

1. Identify structural relationships to other characters:

http://zhongwen.com/?lang=en

2. Based on the basic pronounciation variations identified with the tool hunt down more characters using Google Pinyin:

http://tools.google.com/pinyin/

Enter the Pinyin and work down to the most obstruse characters. Also try variants...

3. Find out about the meaning with the dictionaries of your choice, of course the cool:

dict.cn

4. For the main radical, traditional/simplified variants and the meaning of more obstruse characters you have the indispensable:

http://zdic.net/zd/

5. Important is definately the frequency:

http://lingua.mtsu.edu/chinese-computing/statistics/char/list.php?Which=MO

6. Gather everything, e.g. with MS Excel. Build a formula for generating some HTML that puts the data together and adds colors.

The boundaries I use are: Frequency

< 2,000 --> green

< 4,000 --> orange

< 6,000 --> brown

< 10,000 --> blue

>= 10,000 --> red

Here is my formula I am using

Note: N is the column with the frequency data:

IF(N3<2000;"<font color=green>";IF(N3<4000;"<font color=orange>";IF(N3<6000;"<font color=brown>";IF(N3<10000;"<font color=blue>";"<font color=red>")))) &G3 &IF(H3<>"";" ( "&H3&" )";"")&"@Pron: " &J3&"@Main radical: "&K3&"@Frequency: "&N3&"@Meaning: " &L3&IF(M3<>"";"@Examples: "&M3;"")&"@@</font>"

The placeholder for the linebreak here is the @-character which can be automatically replaced later, e.g. in Word with proper CPod-compatible linebreaks.

Note that the HTML is only interpreted correctly after a re-edit of the post.

What are the major differences between these two products, Wenlin and Pleco?

Pleco is mobile and Wenlin is for computers, and the price, Wenlin $199/£125 Pleco $99.95/£62.50. I've been using the trial versions of each for a few weeks and Wenlin seems more informative regarding Characters, though it's difficult to get a proper comparisson without actualy purchasing both. Any users with experiance on the difference would be much appretiated.