I'm making some changes to the meetup group to expand the scope. One of them is bi-monthly DIY filter photowalk.
What's a DIY filter? Quite frankly, it's anything between your lens and your subject. We now do this in post via photoshop or instagram like programs, however up until the digital age it was all done "in camera."
There's no reason for the old tricks to not work with newer DSLR's, in fact the DSLR's make visualizing the filter results so easy now that there is no reason to not experiment with filters.
Your homework for this assignment is to create 5 filters using things you already have around you, that you can keep in your camera bag. Bring them with you to the meetup. We'll have a photowalk and visualize the 16th Street Mall though our old school photos.
Here's a webpage that will start you off in the right direction: http://content.photojojo.com/photo-projects/ten-filter-ideas-on-the-cheap/
It will be after sunset, so bringing your tripod is advised, but not necessary. Please let me know if you have questions or want any pointers :)