I recently picked up a second project bike and am interested in putting some fun lighting onto it. What are some of your favorite (and reasonably affordable) led lights for the wheels or frame?

Depends on what "reasonably affordable" is, and how much you believe in the idea that cool has no price tag.

Just to start off, here are some of the things I have found.

LED underbody kits. Made for an ATV but can be used on a bike. Note that Google will turn up many more hits for "LED under body kit".
https://www.ledunderbody.com/Million-...hting-Kit.aspx

LED valve caps - require presta adapters.
https://www.niagaracycle.com/index.php?cPath=286

Spoke lights.
https://www.hokeyspokes.com/index.html

More spoke lights
https://www.monkeylectric.com/

If you are OK with DYI projects
https://www.instructables.com/id/Spok...-Wheel-Images/

Really, there are a lit of options available.

Very neat! Thanks for the links... Truth is I'll take a look at any lights regardless of the price .