Jake insisting he'll only help the police solve a case if Leslie gets her job back.
Jake and Des are trying to defuse a bomb, and Des tells Jake that he should leave since Des doesn't want to kill him if he screws up. Jake replies "As annoying as I find you, I would never let you die alone." Veers into Tear Jerker territory at the end of the episode, where Jake is comforting Des as the latter lies shot on the tarmac and bleeding out.
Des' father telling Jake that Des constantly talks about him, and regards him as a role model/surrogate father.
Des buys the remains of Jake's GTO and gets it repaired for him.
Also Jake's basically speechless reaction to this.
A meta example: Allan Hawco announced that Lynda Boyd (Rose) would be joining Facebook, and asked the fans to give her a warm welcome. They happily obliged, and Boyd personally replied to some commenters thanking them profusely. She was quite overwhelmed by all the support and love she received, and regularly interacts with fans (she calls those on Twitter her "Tweetiepies").
In the season five opener, everyone's reactions to finding out Jake is alive.
Tinny telling Jake that he's her father figure, even after she's been pissed at him the whole episode for fighting Crocker.
Des's first line (to the person he was being held hostage with) after Jake rescues him and successfully removes a live grenade from his mouth: "I told you he'd come for me." Aw!
Hood's unswerving loyalty to Leslie and Jake in the series finale. Walter giving Jake a chance to escape from the courthouse by fending off the judge and bailiff is less unexpected, but just as adorable.
Mal telling Jake how much he means to him in "Judgement Day." Particularly poignant considering the abuse they usually heap on one another.
The entire two year's later epilogue in the series finale, which unfolds to the song "Take Us Home."