I'm trying to rec and review a good variety of stories here, so this time around I'm only reccing one story per author.
"Good Vibrations" by Lysandra - This is possibly THE funniest fic I have ever read. Mulder is called down to a strip club to pick up a REALLY drunk Scully. Hilarity ensues, including Scully singing Chumbawumba and Mulder finding a secret (we'll, several secrets) that Scully keeps in the drawer of her nightstand. I was literally CRYING with laughter!
"Above Rubies" by Rachel Howard - this is the first full-length casefile fic I ever read, and its still amongst my favorites. Mulder and Scully are sent to NYC to investigate a domestic terrorism case. Along the way, Mulder is captured by the terrorists, and Krycek shows up asking for Scully's help - Krycek's been supplying the terrorists with explosive gas, and thet're holding his sister as insurance that he doesn't betray them (which he has - come on, this is KRYCEK). His offer - agree to help him free his sister, and he'll help Scully get Mulder back. Also classifies as a Mulder/Scully "first time" fic. Its really great, very suspenseful and angsty!
"Blinded By White Light" by Dasha K. - This is, above and beyond, my absolute FAVORITE post-colonization fic. Usually I hate pos-col, because it almost always ends sadly, or with character death. But this one has a happy ending, and is just...WOW. Earth has been colonized, but after the battle, the aliens have decided to allow a certain number of humans to still live. During the battle, most of Earth contracted a deadly plague. Those that survived were left with almost no memories of their former lives. Mulder and Scully have both survived with no memory of each other and have both moved on, gotten married, and had children. But what would happen if they met again, and memories from Before started to come back? Great story, a really suspenseful climax that will leave you on the edge of your seat, and a happy ending. Definitely worth reading over and over!
"Secret World" by Bonetree - The awesomeness of this fic totally blew me away when I read it for the first time last week. Its the sequel to "Goshen", but you don't have to read it to understand this story. Scully and Mulder are called in to help investigate a US-based Northern-Irish freedom terrorist group that was once connected to the IRA. Mulder is assigned to the surveillance team, while Scully is sent undercover to work for the head of the group, Owen Curran. Another fic that will keep you on the edge of your seat and make you want to stay up all night just to finish it!
"Eleventh Hour" by Rachel Anton - Ok, so usually time-travel fics are REALLY cheesy, but this one isn't. Scully is shot and killed by a suspect, and Mulder is sent to prison for murdering the suspect. A fellow inmate offers Mulder an opportunity he can't pass up - a chance to go back in time to prevent Scully from dying. But rather then sending Mulder back to the moments just prior to Scully's death, he sends him back to Scully's freshman year of college. This fic is amazingly done, and manages to stay as in-character as possible for such an AU fic.
More later - I'm at work typing this from my Blackberry and now my thumbs are hurting!