I'm currently slightly experienced but I still call myself junior. Here is what I appreciate of my employer:

• Buys me books. I have a diverse taste from C# to perl to C to Asm to database design to tsql etc. Book prices vary from $20 to $50. This usually requires a PO and approval and such.
• Allows me to critique current projects. I've re-written a few project to be MUCH cleaner through the experience I gain. Each time I document why I made those changes. Every now and then I re-write my re-writes. It's amazing to see how much you change. I do this one on my own. I initiated it.
• A fast computer and a 24" monitor. This actually helps a lot, but for any developer. Less frustration and more code on the screen. Monitor also rotates for those kinds of days.