To create smart tags without writing programming code follow the below steps:

Smart Tag
1.Download this file by right clicking smart ekanna
2.Save this file in the path C:\Program Files\Common Files\Microsoft Shared\Smart Tag\LISTS\1033
3.Open MS-Excel and go to Tools–>AutoCorrectOptions–>SmartTags–> Tick on Smart ekanna as shown in the picture. In Excel 2007 press Alt+F+I+Proofing+AutoCorrectOptions
4. Now close and re-open MS-Excel and type in any cell the word ekanna you will see the below figure.

ekanna Smart Tag
Now how to customize this to recognize your own key words instead of ekanna?
1.Open the file “smart ekanna.xml” with notepad and edit Term Lists and Action caption names with words of your choice and then save and close
2.Now open the MS-Excel type the keyword in any cell you will see the contextual menu i.e. smart tag menu
Is it possible to assign Excel VBA Macros to these menus instead of Web URLs without writing programming code in VB, C#, .Net etc. by merely editing XML file?
At present NO!
Why?
Read this article from Microsoft
Does Smart Tag List tool allows to define search patterns in addition to search lists/ key words ?
Yes. Read this article from Microsoft


