Title says it all. I, for example, would've like to see:
Gohan goes with Bulma and Dr. Briefs to the Nemuria Ruins in the Break Wasteland Desert to rescue C-6 as he promised him before facing Vegeta and Nappa, C-6 will get an upgrade and will be free to travel around the world as he wishes.
Vegeta is on his onslaught of Frieza's Army while Goku is gone and is forced to face all sorts of memories he had while serving the tyrant (we get to see more of how brutal were his life then from the bad treatment he got since childhood taught to spare nobody throughout being bullied with his Saiyan allies by the Ginyu Force on the cafeteria).
Gohan who is waiting for Goku to come back is wandering and meets with some of the orphans he met back then, seeing they're all good now, and learns that Pigaro is now a Police volunteer who patrols to oversee the children he once led.
Master Roshi, Oolong and Umigame go on a journey to gain the Dragon Balls for wishing Roshi a wife so he'll "settle down", only to disagree about her race/looks when Shenron is summoned, then the Pilaf Gang who rivaled them in this episode get the upper hand (after Mai claimed she's too old now to get a husband, Pilaf is ashamed at himself due to being older than her) and wish to be "young as can be" and be turned into babies that are left behind by the heroes.
Why Bulma and Yamcha broke up for good (I'd say he signed some busty "too outgoing" lady fans on the chest as they requested while Bulma was buying clothes in the West City Mall and when exiting the store Bulma saw that and his flirty attitude as cheating and threw him for "good" = if you like the SSJ frenzy that gave life to Trunks).
Tien and Chiaotzu come to Kami's Lookout and ask to go for a round of training for the Androids in the Pendulum Room, where they fight against all the creatures Gohan and Krillin faced on Namek (and along the way - Zacro and Raiti), only to be squashed by 3rd form Frieza, realizing they still have a long way to go.
Post Cell Games
Gohan's growth in the 7 years where Goku was in Other World, like have him "dating" Lime (that girl whose village was terrorized by Tao Pai Pai) for a couple of episodes before both sides realize it isn't working for some reason and moving on.
Goku's training in the Other World, seeing new techniques from other fighters, adventures with Olibu and Pikkon, meeting the Metamorians, etc.
Bora and Upa's village fell under the threat of Colonel Silver and his faction who wishes to wipe their tribe out so he'll be able to sell the ground to realty billionaire with Gohan comes to their rescue.
How Krillin met with Android 18 before their romance bloomed.
Tien and Chiaotzu go on a mini-arc adventure to save a princess of Chiaotzu's "kind" from a demon that trapped her in his stronghold with Launch (who ran across them earlier on while they were farming) holding them back a little while she desperately tries to convince Tien to marry her (I honestly wish he'd say "Yes" and give that old character the family she wants to have).
Yamcha's winning another baseball title with his team while surpassing his ki to play on the "normal people's" league due to a bet with Mr. Money (who saw him flying with Puar) and finding it is much harder to play the game that way.