With "cocotape" you can use a standard coco cassette cable to transfer files or games from your pc directly to your color computer.
CoCoSID is a program I wrote for the Tandy CoCo 3 that more-or-less mimic the sound of the Commodore 64 SID sound chip. The music used here is a hand-converted version of the original C64 Commando by Rob Hubbard. The DSK can be found here to play on emulation or real CoCo 3: http://www.coco3.com/community/wp-content/uploads/2010/02/REMDISK_cocosid.zip
My homepage: http://sites.google.com/site/rveilleux/coco3home
At the 19th annual "Last" Chicago CoCoFEST! in Elgin, IL this past weekend (May 15-16, 2010), the guys at Cloud-9 had an FPGA board they were playing with, which was set up to act like a CoCo 3 (including support for GIME chip and BASIC and all that). In this video, they explain who is behind the project. It's fascinating!