The following is a list of the current bounties offered at my megadungeon open game table, as they are presented to my players. Well, they get everything all nicely printed out on individual half-sheets of paper, but you get the idea. I hope some of them may inspire you for your own games.
Part of this is a lesson I have heard, but not entirely completely internalized: whenever possible, have something physical to hand your players. Tangible objects are supposedly much more interesting to them than mere descriptions in the air. As one hears often in Westeros: words are wind. This particular technique, the bounties on paper, suffer somewhat from still mostly just being words, though if you can interesting them up by trying to get as close as you can to the actual handwritten documents (mostly with creative font choices), that helps.
A side story: one benefit to using LaserTron tokens for mini bases: I had a couple left over (which I did paint on one side, intending to use them for swarms or miscellaneous markers or something), so when my players tried to squeeze money out of a particularly unwealthy viscount, I had five coins on hand to drop on the table and say "This is all the money I can spare".
My next idea to liven things up is to include bounties that are just pictures, no words. Not everyone who wants to post a bounty is literate, after all. Even Sir Bigglesworth counts as literate, if only barely. But this is a major challenge for the DM to try to convey instructions without using words, and to the players to understand.