Heres few ideas. I took this list off another post of mine but I updated it.
(Some of these ideas are "Pack" ideas and list selections")
Buy Exp scrolls with your guild marks
Simplely just trade players EXP scrolls of DoH,DoL,DoW,DoM. Each Class Selection = type of EXP scroll.
Weaver Guild Mark Points= DoH exp scroll
MRD points= DoW exp scroll
Miner points=DoL exp scroll
5000GM for 1 tier1 exp scroll
10000GM for 1 tier2 exp scroll
1 Ifrit Totem= 20000GM
1 Moogle Totem=20000GM
Spirtbond+1 Buff (Lasts 3hrs)=500GM
Spirtbond+3 buff (Lasts 1hr)=1000GM
Repair decreases rate -50% buff (Last 3hrs) 500GM
Meals Eaten +10% buff (Last 3hrs) 500GM
1000GM Convert into 10 Faction Points
500GM Convert into 100 seals
Normal food Items turn into HQ stats buff (5hrs) 500GM
Status Up! Buff All Stats Str,Dex,Vit etc +10 (3hrs) 500GM
Crystal Gain Doubles Buff (Earn 2x the amount of crystals (3hrs) 500GM
Treasure Hunter+5% buff (3hr) 5000GM (Effects this person that claims the mob)
1 Anima for 250GM
10 Anima for 1000GM
DoL Havesting Amount Increassed (better chance to earn more Materials in Gathering) (5hr) buff 750GM
Crafting Amount Increassed (better chance to earn more Materials in a Craft) (5hrs) buff 750GM
Materia Harvesting. 1shot buff 5%~7% to make Materia to its max stat Materia (Str1~6 etc). 500GM
Movement Speed buff (1hr) 250GM
Movement Speed buff (10hrs) 1000GM
Repair are free today (24hrs) All Repair Costs from NPC are free 1000GM
1GM=10gil
10GM=100gil
100GM=1000gil
1000GM=10000gil
Gil Finder+10% 3hr buff (Mobs drop 10% more gil) 250GM
100GM Free Rental Tickets for Chocobo's (Like with FFXI Can trade other players such as new players toget no gil cost rental chocobos)
200GM Free Airship Tickets 1
30000GM Free Airship Gold Ticket (Can use Airship 20 times without fees)
Aeth Leve Exp Buff+ 500GM (Earn more exp in Leve Quests)
Music Player(Plays any Track within the City only you can hear it.) 100GM
Gathering+ (Doubles chances to DoL a location more amounts at a time without having to change to another location.) 750GM.
5000GM for each piece of Onion Armor (Not Including headpiece)
Refresh buff (5hr) (1MP a tick a second) 250GM.
10GM for Fireworks
50GM for Weak Food
100GM for Decent Food
250GM for Good Food
5~80GM for Types of Arrows for 1 Each
Enchance (Refill AF/Weapons kinda like Skyrim/Soul Gems) (Thats if they change anything with armor system)
Chocobo Food Boost+20% buff (3hrs) (When you feed chocobos in Chocobo Escorts it heals more) 500GM
Not many more ideas I can think of which aren't Class~Equip based. If I think of anymore ill add it to the list.