Leixões SC:
Leixões SC is a club from Matosinhos (Porto) with a great history and great support.
In 1961, they defeated their "giant" neighbour FC Porto on the final of the portuguese cup. The stadium, full of FC Porto fans, was perplex... Except for a little stand of Leixões supporters. (video here:
https://www.youtube.com/watch?v=uOQia9hdacg)
In 2002, when Leixões was on the third division, it reached the final against Sporting. Lost 1-0, but as Sporting was already qualified for the Champions League, Leixões qualified for the UEFA Cup, being the first (and so far, only) club in a third division doing it. They eventually got promoted to the second league, and later, in 2007, to the first league, where they played for several years.
However, in 2010, they got relegated to the 2nd league again, where they are now, fighting to avoid relegation. But that doesn't take people off the stadium: They keep supporting their team, sometimes filling up the stadium. I think the club also gives free tickets for some games to the fans (obviously, that days the stadium is filled up).
Let's hope they don't get relegated.
Link of the kits:
http://imgur.com/a/MIWwf
Previews: Home/Away/GK