So I had my D-LINK DIR-655 router give up its routing duties recently and had to replace it. (I ended up replacing it with a Netgear dual band router and love it so far) It was making me restart it about once ever couple days, then daily and then at the end every couple hours. I found this set of instructions on how to set my router as a wireless N access point. It should work for most home routers though these instructions are for a D-Link DIR-655 specifically.
I had a failing access point in the house I had been wanting to replace for a while so figured I would try it out. It works like a charm. You basically turn off the DHCP server, virtual servers and any port forwarding you had setup and give the router a new internal IP Address. Then plug an ethernet cable into one of the LAN ports (Do not use the internet/WAN port when using it as an AP) and you are done. So far it works great as a switch and AP though it cannot do its routing duties anymore.
This bumped me up to 56Mbps wireless in the house and saved me from buying a new wired AP for the house as well.