Here are some links to some great public feature scripts demonstrated at a recent virtual Onshape user group meeting.
Project Body by @MBartlett21
https://cad.onshape.com/documents/201b33ee5450cefbca3b34b8/w/95004b1f32bddc1e032970e5/e/03f0c71d4856a8408c7766a0
Calculate Bounds by @Jake_Rosenfeld & @MBartlett21
https://cad.onshape.com/documents/2ce3e64026df1ac7e63b98bd/v/fbde21af6c536247be42fc4a/e/74ed94c52f61d01d37dc9f17
Selection Fillet by @Evan_Reese
https://cad.onshape.com/documents/03d360e7ad4f6762d65fac6f/w/ea253be969c16f80b27583db/e/7aa592d4ddb8c61a41a92b43
Attractor Pattern by @Evan_Reese
https://cad.onshape.com/documents/ca03eaf542826bb98f6cc90e/w/dda165f92e2ad786bd53d97a/e/9b97d9037f0e0bb481cf6111
Freeform Spline by @Evan_Reese
https://cad.onshape.com/documents/cd51f29c6937305f86a9df95/w/86ce0e7568faacfe3963e35b/e/8589c9de769225e856825ea9
Transform Pattern by @konstantin_shiriazdanov
https://cad.onshape.com/documents/25a0a6dfaa76e64574a5e0db/v/8217d6d96ccc324b8dd86160/e/4c62c06c4e0e4db3703a2d4c
Multi Mate Connector by @konstantin_shiriazdanov
https://cad.onshape.com/documents/5d8da63844bedebe5cff72b1/v/a2f8d68037aff39e9d20f7a1/e/11dcab8f665add80b9aced0a
Measure Value by @konstantin_shiriazdanov
https://cad.onshape.com/documents/77baa8153589a7fc5f289829/v/33ba34fba75bf5f4ba08ed63/e/181cb871f3008e6b885df46a
Pattern & Sweep by MichaelPascoe
https://cad.onshape.com/documents/76442daf92ce43df74883ec6/w/2f4ea4d52c5fb26051e11c55/e/d072106a68c04fc5d0a6862c
Intersect Views by MichaelPascoe
https://cad.onshape.com/documents/1755463e12cab51e4a5de51f/w/07865f22b67cc44e473c99a3/e/302fb7288b77057ca30414fb