I do agree that the "If Code" series are cool looking, but to be honest I only like the Ayaka one since it has a real Negima! related story instead of the usual "your da man" of the others.
Since we all like the Dark-Evangel so much, these are what I think are some of the best doujinshis out there and in dire need of scanlation (Hopefully someone will)...
Another Gambler Club's entry:
Gorgeous art and a very convincing story:
This one might have been very well the real origin of the Dark-Evangel:
The scans I have for this one suck a bit, but the story and art are cool:
There are very few doujinshis out there featuring Chachamaru, but it's not that surprising since she's a Gynoid... Good thing that Big Boss' Gekki-Evangeline Ikka features her and ChachaZero (Who's an even rarer H-doujinshi protagonist).