This is a semi-strong validation of e-mails for danish national characters as well. It is not perfect, but decent if needing a solid validating of an email, and I am constantly updateing it for personal use.

Note: Beware of the line breaks added

 ^[0-9a-zA-ZæøåÆØÅ][\w\.\-_æøåÆØÅ]*[a-zA-Z0-9æøåÆØÅ\.\-]@
a-zA-Z0-9æøåÆØÅ]([\w\.\-_æøåÆØÅ][a-zA-Z0-9æøåÆØÅ])*\.
[a-zA-ZæøåÆØÅ][a-zA-ZæøåÆØÅ\.]*[a-zA-Z]$

Yes, I know it is (far) from perfect, but it works for some of the reasons I encounter.
Also - remember, sometimes a loose validation is much better, if you can't validate completely - however, there are times where a stronger, more restrictive validation is useful.

At least for me :) 

Made these regular expressions some time ago to parse/validate numbers in text.

Validate number with comma as decimal pointer, and period as group separator:
^(\d+|([1-9]|[1-9]\d|[1-9]\d{2})(\.\d{3})*)(,\d{1,2})?$

Validate number with period as decimal pointer and comma as group separator:
^(\d+|([1-9]|[1-9]\d|[1-9]\d{2})(,\d{3})*)(\.\d{1,2})?$

Hope they are useful.