To restore the default KMenu:

rm ~/.config/menus/applications-kmenuedit.menu

I found an article describing how to tweak how Kicker looks. I wrote about this before but this site includes a few tips the KDE wiki article does not include.

Interestingly you can add some text to your KMenu button:

[KMenu]
ShowText=true
Text=Some Text

That looks hideous, so I don't use it. But you can. I do like making my menu icons bigger, and removing the section titles though. Combined with the Domino KDE theme to give it nice rounded edges and some Buuf icons, I think it looks nice:

This wiki entry has a LOT of really good tips for making KDE look nice. For example making your K-menu's icons bigger (which I've ALWAYS wanted to do) and getting rid of the K-menu's ugly category headings can be achieved by editing ~/.kde/share/config/kickerrc and adding/modifying the [menus] entry:

[menus]
MenuEntryHeight=32
ShowMenuTitles=false

After going into KControl, Desktop -> Panels -> Menus and turning off pretty much everything, my K-menu looks like the default Gnome menu:

There are options for changing the order of OK/Cancel buttons, changing the order things appear in your taskbar, etc. I also found disabling "archives as folders" in Konq's sidebar to be useful.