These are gen recs especially starring Neville Longbottom, as well as any other Longbottoms. Consider them pure gen unless otherwise noted.
A Thousand Wishes (G?) by Hannelore. Neville, folding paper cranes to make a wish. Sad. One shot.
Aetiologica (PG-13) by lalejandra. After Harry kills Voldemort, Draco finds out some things about his ancestry and Neville offers the hand of friendship. One shot.
After the Screams (PG) by Triskelion. The aftermath of the Longbottoms' torturing. Sad. One shot.
Alternative Therapy (PG-13) by lyras. After the War, Neville comes around to do Harry's gardening. Sweet. One shot.
Assumption (G) by Magnolia Mama. The funeral of Harry Potter. Surreal. One shot.
Bibbed Egg Owls, Lot Mourns (G) by kaalee. Neville does anagrams to figure out what his mother is trying to tell him. Sad and hopeful, all at once. One shot.
Blackpool Pier (G) by Triskelion. The day Neville was thrown off Blackpool Pier and almost drowned. Sweet, and angsty. Two chapters.
Blood Speaks (R) by Northlight. Neville Longbottom considers his parents. Angsty. One shot.
Christmas Shopping (G) by shadowycat. Neville tries to find just the right gift. Sweet. One shot.
Civil Disobedience (PG) by Hannelore. Neville has a question for Snape. Cute. One shot.
Dulce Et Decorum Est (PG-13) by Lady Jaida. Slash is listed as a subcategory, but other than Lily/James it's pure gen so far. This is an AU in which Neville is the Boy Who Lived. I like well thought out AUs, and this is one of my favorites, even though it's barely begun. Novel length, WIP.
Green Thumb (G/PG) by Bryonia Alba. Neville starts his first garden and recieves his first sweets wrapper because of it. Bittersweet. One shot.
Harry Potter and the Legacy of the Light (PG-13) by Gramarye. This fic crosses Harry Potter with The Dark is Rising and does an admirable job of living up to that expectation. Basically, it turns out that Voldemort threw his lot in with the Dark. Harry and five friends must fight against him with the help of Will Stanton, the last Old One and professor at Cambridge. Very well thought out and very well executed. Novel length fic, and be sure to read the short prequel as well.
His Father's Wand (PG) by ReaderRavenclaw. Neville waits for his grandmother after the events of OotP. Good character sketch. One shot.
His First Fears (G) by Mishty. Neville considers what he's afraid of. One shot.
Hocus-Pocus (G) by rinsbane. A new boy comes to the orphanage. Creepy. One shot.
How the Story Ends (PG-13) by Sioniann. Includes some references to het and slash. Neville can't remember, so he has to make up memories. Beautiful and lyrical. One shot.
Jehu (R) by Nathan Stack. Includes one or two references to relationships. Harry is out hunting Draco Malfoy with his crew. A wonderful, fantastical takeoff of Moby Dick, though you don't need to have read that book to appreciate this fic. One shot.
The Last Mudblood (PG-13/R) by furiosity. Voldemort has won the war. Neville Longbottom is a Death Eater looking for Hermione Granger. But things are not always as they seem. One shot.
Missa (G) by Mirabella. A series of post-War vignettes. Bittersweet. One shot.
Neville Longbottom and the Moment of Truth (G) by Dien Alcyone. Neville finally goes off on Snape one day in Potions class. One shot.
Preferences (PG) by eumenides1. Based on Bartleby the Scrivener, it's a post-war fic that's not what you would expect. It has a sequel, written in modern language, called 2001, but that's a bit Harry/Neville. Both one shots.
Scars (G) by Winding Path. Neville and Madam Pomfrey have a talk. Bittersweet. One shot.
Scrap (G) by Sternel. Another bittersweet Neville fic. Short one shot.
Strange Bedfellows (G) by McKay. There's a warning for slash at the top of the page, but this story is pure gen. During PoA, Neville gets locked out of Gryffindor Tower and finds a large black dog. Cute. One shot.
The Substance of Things Hoped For (PG?) by Catrinella. Neville nurses his grandmother through her last sickness. Very Neville-ish, in a good way. One shot.
Uncle Algie Makes A Call (G) by BrieflyDel. When Neville was eight, his Uncle accidentally dropped him out a window. This is the story of that encounter. Well written. One shot.
Unfinished Business (G) by Cynthia Black. This is another Neville fic, in which he ponders on the wand he broke in the Ministry of Magic. One shot.
Unforgivable (PG) by darkriddler. Neville thinks about the Cruciatus, and his parents. Angsty. One shot.
With Quill In Trembling Hand (PG?) by Ciircee. Set during PoA, Neville needs someone to buy him some Sugar Quills from Hogsmeade. Sad, but with a positive resolution. Long one shot.