Good food in KL

Jalan Imbi
Oversea Restaurant (Chinese) - it's behind the Westin area, on Jalan Imbi. Very good Chinese food - almost anything on the menu is good. I really like the cod fish.
KTZ (Chinese ice desserts) - after dinner at Oversea, cross the main road (Jalan Imbi) to get to KTZ for Mango Ice. It's basically mango puree with shaved ice and pieces of mango. There are other flavours too but my fav (and I believe still the best!!) is mango.
Meng Kee (Chinese) - this place is behind KTZ. Very famous for beef and prawn noodles, however, may be a bit risky coz you need to go with a local chinese who will know how/what to order. If they know you are foreign, highly likely they will overcharge you :-)

Tengkat Tung Shin - this is a small street 2 rows parallel to the main Jalan Bukit Bintang.
Sao Nam (Vietnamese - Halal) - One of my favorite places. It's actually a row of colonial shophouses which have been refurbished to create lovely little restaurants. I like the Pomelo and Prawn salad, and the duck breast with orange. Best to order a few different dishes and share.
Old Siam (Thai - Halal) - next to Sao Nam. Have not eaten here but keep hearing from people that it's very good.
Famous Beef Noodles Stall (Chinese) - excellent place for late dinner/ supper. It's a stall right at the end of Tengkat Tung Shin. It's become famous now, so it's quite clearly marked as the "Famous beef ball noodles" :-) Hygiene is subjective, though I've never heard of anyone who had problems after eating there, but be careful if you have delicate stomachs.

Changkat Bukit Bintang - this is another small street very close to Tengkat Tung Shin.
El Cerdo (European) - absolutely the ONLY pork heaven in the universe!! It's totally porky from items on the menu to decor on the walls (even in the bathrooms!!!). Very good quality food, and very tasty!! Should try to make reservation as they are usually packed. +603 2145 0511 2. Ceylon Bar (Western/Local) - the only reason to go to this place is the all-day brunch on Sunday. For RM 26, you get a very filling meal of pork sausage, bacon, eggs, etc etc. Starts late - go after 11.30am only.

Other great places
Yut Kee Coffee House (Hainanese) - Jalan Dang Wangi. Very very good traditional coffee shop, gets packed on weekends, so go around 11am or after 2pm. Pork chops here are legendary, as is the Belachan Fried Rice (very spicy!), and noodles overall are very good too. Also make sure you have the cakes for dessert - marble cake or Kaya roll (kaya is a sweet jam made from coconut milk and eggs)
Souled Out (Western/Local) - this place in Sri Hartamas is very popular and great place to hang out and chill. Good mix of locals and foreigners, mostly groups of friends relaxing and having a good time. Food is generally good, and great selection of cakes for dessert. The Hartamas area itself is a lively night spot with lots of restaurants, bars, pubs, etc.
B'Sentral (Indian) - this place is in Brickfields, opposite KL Sentral station (you can take the monorail from Bukit Bintang to KL Sentral Station and walk from there). Must try Roti Canai - this is almost Malaysia's national food, Claypot Biriyani, Roti Prata, Mango Lassi (drink). The tandoori and other oven-baked chicken is really really good too.