The folks over atxda-developers have a neat set of cab files that allow you to Change the Default Font in WM6. You may not like the default Tahoma font and want another look on your device so they have three cab files you can use to make the change easily. And if by some chance you don't like the look, just remove it and it will return to the way it was.

You can see examples of the Default, Calibri and SegoeUI as you view the Start menu right after the break AND there is a step by step on how to do it manually if you have that special font you really want to use.

Of course you can do it manually too and that is good if you have a really special font you want to use that is not one of the three cab files. To do that, just follow these steps outlined by Merlin on how to change the default font.

Using the default Vista font "Segoe UI"
1. Copy your font file (usually *.ttf) into /Windows/Fonts. Be sure to note the INTERNAL name of the font (find it out by double-clicking on the file in Windows)
in this case "Segoe UI"
2. Using your favorite registry editor, navigate to HKEY_LOCAL_MACHINE\System\GDI\SysFnt
3. Find the key named "Nm". Replace what's in it (usually Tahoma) with the name of the font, in this case "Segoe UI"
4. Repeat III for "HKLM\SYSTEM\GWE\Menu\Menufnt\Barfnt" and "Popfnt"
4.1 Under HKEY_LOCAL_MACHINE\System\GDI\V1
- look for something like FontAliases. The keys inside represent the font "choices" -you have (which default to Tahoma), and look like Arial:-12. Change the value -from Tahoma* to Segoe UI*.
- Rinse and repeat.
5. Reset
And that's it ! The Segoe font renders much more easier to the eyes with Cleartype (and the spacing is really nice)

Check it out here at xda-developers and download TTF myriad.CAB, CALIBRI.CAB or Segoe UI.CAB