Page 4 on the "Post your home screens" thread has a QR code for downloading "Fancy Widget" which has is HTC sense like clock and weather widget that looks really nice. Its a good option if you are using TouchWiz, I didn't like the other clock widgets.
Samsung has a couple of useful apps on the app store, car home and desk home. The car home just shows a limited menu for stuff you would need while driving, google maps, voice search, etc. Desk home is similar and shows a big clock, its good for turning your $200 smart phone into a desk clock. I think you search for "Samsung" to find them.
Appbrain app is really useful. When I hard to hard reset my phone it kept a list of all my apps and I was able to download them all again really quickly instead of trying to search through the app store for them.
Oh yea, one more tip, download a barcode scanner app so you can install apps using QR codes.