I'm recommending Martha Jones-centric fics all this week but they're not all Martha/Ten.
Story Bombardment of Positive Ions
Author: Carmen Sandiego
Author Summary: Martha Jones and the UNIT Christmas Party.
Characters: Brigadier Lethbridge Stewart, Harry Sullivan, John Benton, Liz Shaw, Martha Jones, Sarah Jane Smith, Second Doctor
Rating: All ages
Word count: 2601
This is a very humorous story about a Christmas get-together of the Doctor's former Companions at the Brig's house with a fair amount of amusingly snarky point-scoring from earlier Companions. And Martha gets to meet the Second Doctor:
Martha looked up. A sprig of mistletoe. Oh. Well she couldn't, obviously. And he -
The Doctor kissed her, and it was soft and gentle and entirely welcome. When he pulled away, Martha looked into his eyes and found no apologies or regrets or excuses. If anything, he looked rather pleased with himself.
"That was...nice," she said, unable to keep the smile from her lips. "Much nicer than last time."
"Last time!" said Jamie, poking his round the door. "Here, Doctor, what's this about then? You dinnae see me going around kissing lassies I've just met. I think you’ve got some explaining to do."
I've read this about 6 times since it was first posted and it makes me laugh every single time.