Shipping!

My personal favourite ships:

- Sparity (Spike x Rarity): Spike's got a crush on Rarity, and sacrifices a lot for her (using his time helping her create clothes, giving her his Fire Ruby, doing miscellaneous chores). Meanwhile, Rarity has shown moments of affection for him, though admittedly has used his crush for personal gain; if fanfics can show her overcoming that, and actually fully returning the drake's affection, I believe this pairing could work out quite well.

- Fluttercord/Discoshy (Fluttershy x Discord): Fluttershy doesn't spend a whole lot of time with anypony; sure, she has spa sessions with Rarity and Rainbow has been BFFs since foalhood, but the only non-critter being who spends a significant amount of time in her cottage is the draconequus, Discord. Fluttershy's also Discord's only real friend (being the one to tolerate his antics and give him the attention he craved, in order to reform him), and Discord has also shown jealousy when Fluttershy took another friend to the Great Galloping Gala.
If they both realised how much they actually meant to each other, I have a feeling the pegasus and the draconequus would be happy together.

- Flutterdash (Fluttershy x Rainbow Dash): the two have been friends since foalhood, when Rainbow protected Fluttershy from bullies, picking on the older filly's then-inability to fly. Since then, Dash has served as a source of inspiration and protection for the timid pegasus, while Fluttershy provides the daredevil with the opportunity to relax and embrace peaceful moments.
Heck, Fluttershy only joined the water-sucking tornado when Twilight said "Do it for Rainbow Dash", when the pegasus doubted her 2.5 wingpower could make a difference for the longest time.

- Lunashy (Princess Luna x Fluttershy): they're both reclusive mares, afraid of what will come out should their buttons get pressed, and not exactly the best at talking to others (for Luna, as equals - the 'nobles' who visit her Night Court are a different matter).
Fluttershy can get downright mean, inconsiderate and forceful when angered, as Iron Will's lessons showed; her infamous Stare also has the power to make most targets cower and drown in their regrets.
Princess Luna still suffers from being possessed by Nightmare Moon, and created the Tantabus as a constant form of self-punishment.
Needless to say, neither likes what they could turn into, and - since they share quite a bit, in terms of personality and 'other side of the coin' - they could work out well together.

- Twilestia (Twilight Sparkle x Princess Celestia): Twilight Sparkle spent most of her formative years as Celestia's prized student, and thus a student/teacher crush is quite reasonable. However, seeing as how Twilight is now an adult, she should've been able to overcome her fear of disappointing her mentor. She has not; for example, she was horrified of being tardy and offending Princess Celestia, leading to the Want It, Need It debacle; Twilight Sparkle will also do pretty much anything Celestia says.
As for Celestia, being alone for a millennium and having her previous student - Sunset Shimmer - turn into a self-absorbed, power-obsessed jerk has left her quite fragile, and ruling over countless generations of ponies cannot be easy. The princess needs someone who loves her for her, and not for her power or title. Then comes along a purple unicorn filly, who Celestia takes as her student. Eventually, since the two have spent so much time together, the teacher/student bond would change to that of a surrogate mother/daughter bond, though the Solar Alicorn does respect Twilight's bond with her actual parents - this is why Celestia cared so much for Twilight's safety early on. However, when Twilight gains wings and becomes Princess Twilight Sparkle, the two are on equal footing, allowing this relationship to surpass any semblance of 'superior/inferior' mould. Celestia still clearly loves Twilight, and Twilight loves Celestia - seeing this become romantic love is something I want to read.