I really sympathise - I'm 21w with my first and just had no idea how debilitating it could be. Mine stopped at 17w. In no particular order, I found all of these helpful at some point:
Fizzy drinks - get calories into you, but they don't actually have much in them, which might not be nutritionally great but means there's less your stomach can object to!
Dry crackers - cream crackers, water biscuits or those salty cheesy cracker thingies someone else mentioned. Just make sure you drink plenty because bringing those back up without adequate dilution is HELL. (They clog like cement - sorry, but it's best to know!)
Plain biscuits - digestives, rich tea etc. I like the Nairn's ginger oat biscuits too - I find normal ginger nuts way too sweet when I'm sick.
Rennies - I know they're meant for indigestion, but I find them soothing!
A hot water bottle on my stomach helped too, and keeping very very still! Not always practical, though!
Probably the best advice I was given was "eat whatever the heck you want and don't worry about perfect nutrition". It's better to get something into you than nothing, so if you want crisps or microwave pizza, go ahead! Hope you feel better as soon as can be expected!