Things I've done include:

• LED the instrument cluster* and HVAC control cluster
• LED all the interior lights
• LED the rear lights
• Install roof racks
• Stainless steel exhaust system
• Got all black (LX style) door handles
• Upgraded the speakers because I thought I blew the old ones. I didn't.
• Front and rear dash cam (Although the parking lines aren't helpful)

Things I'd like to do include:

• Trailer hitch (although I'd go with a Curt one, not the Honda one)
• VTEC THAT BAD BOIII (CRVTEC)

There are some other things too. If you have the LX, you can buy a remote for keyless entry (LX specific apparently) because it already has a keyless entry system built in. It just doesn't come with a remote.

There are some other official accessories, though many tend to be surprisingly destructive. (Drilling holes, cutting things with hack saws, etc.) I'd recommend checking out this Honda Accessories site.

If you live in the northeast, I do recommend a stainless steel exhaust system because the regular steel one rust out at the drop of a hat. Although I'd be careful where you source parts. The header I got didn't fit right and the muffler I got failed quite quickly. :/

Initially I just replaced the door handle I broke in an ice storm, but then I liked the black look and replaced them all.

*For the PRINDL21 lights, I replaced the bulbs with these. For the rest of the dashboard lights I got Two of these and One of these. To do the HVAC controls I needed another set of the T5's and for the cabin lights I just needed one of these.