Great lightweight flat pedal for the kids. 220g and around $30. Ti axles are available for further weight loss.
Xpedo XMF08TT Pedals
Xpedo XMX24MC pedals
These pedals offer a large comfy platform, 7 replaceable grippy replaceable pin on either side (spare set of pins provided with pedals) and are nice an thin, so you can get your set and center of gravity lower....
Lightweight flat pedals
VPone hank pedals - 180g - 'carbon' body, single sided, not sure how these would work. Light and cheap ($30);
Shimano M540 SPD clipless pedals
This pair old and a bit dirty. Total weight 352g for a pair/set. Not a light set of pedals but have worked flawlessly for many years.
AEST titanium spindle flat pedals
The model I have are "YMPD-10T". Spindles are titanium and weight is 284g. They have a nice large platform with 10 replaceable aluminium spikes on each side. The platform is larger than the J&L ...