I think it's quite interesting how many English words have been imported/distorted in Japanese... Here are some I've found:
 
スチ／スチュワーデス: スチ being the short form, this word comes from "stewardess".
 
リモコン／リモートコントロール: Another word that has a shortened form, this is similar to パソコン. Comes from "remote control".
 
トラベル: In this word it's a combination of the last two that threw me off at first. This actually comes from the word "travel", with 'b' and the Japanese 'r'/'l'-sound substituting 'v' and 'l'.
 
イベント: Comes from "event".
 
ベートーベン: This was a headscratcher for me, as when you transliterate it it becomes beetooben; not very similar to the original name "Beethoven".
 
アナ／アナウンサー: This was also tricky because the first time I saw it it was in the short form. Just アナ sounds like a name, and I originally thought it was that, but then I saw it attributed to many different people. After a while I saw it in a context that also mentioned the full form アナウンサー and it was clear that it came from "announcer".
 
ヘルスケア: "Healthcare". There is also ヘアケア, "haircare".
 
アラート: "Alert".
 
キャラ／キャラクタ: "Character". I should clarify that it seems to be used only for describing the physical character, not having character as in "moral or ethical strength".
 
サムネイル: This I wouldn't have had the foggiest what it was unless it was in a context with many small images... "Thumbnail", as in a thumbnail-image.
 
サントラ／サウンドトラック: The longer form should make it clear that it comes from "soundtrack".
 
コラボ／コラボレーション: "Collaboration".
 
メアド／メールアドレス: This I saw in the Densha Otoko drama. The short version of this is particularly tricky since it doesn't really hint at what the full word could be ("mail-address").
 
セクハラ - I don't know if this has a long version or not, but be sure not to get into "sexual harassment".
 
レス: I'm not sure of this, having not confirmed it's meaning, but I've seen it in the BBS context, so I assume it would come from "response"/"respond".
 
スレ／スレッド: A bit of a weird one. Comes from "thread", with 's' replacing the English 'th'-sound. Tricky.

Impressive! I didnt realize those were loan words.

Quote from Pooh Admin on Mar 28^th, 2006, 3:29pm:

That was also a pretty good list, but it was a bit hard to read when it was written in romaji... some of the transliterations seemed to be a bit off, like "Rasshua Ahwar", 「ラシュ・アワー」 I'm guessing, would be better to write "rashu awa" (or "awâ" if you want to stress the long 'a').
 
I think "Kukki" 「クッキー」 is "cookie", and "Saa kuru" 「サークル」 could be as easy as "circle".
 
Note also that "Taifuu" doesn't come from English, but it's the English word that comes from the Japanese 台風!  
 
An interesting one that was new to me was "Nau Na Firingu", is that 「ナウなフィーリング」? Pretty interesting in that case where they're using "ナウ" as a な-adjective!

Naumanzou appears to mean a mammoth. Mammoth's molar means the chewing tooth (back tooth, molar) of this massive creature.

I've been meaning to ask this question for some time now.... so here it goes; Jacke is that you on your icon? O_O

Quote from acjama on Jul 1^st, 2006, 4:38am:

 
It's from the common name for Palaeoloxodon naumanni, "Naumann's Elephant." It's a kind of small elephant whose fossils are found in Japan. You must be reading some unusual things!

More!
 
ムック: Combine a magazine with a book and you get a "muck".
 
オブジェ: An object.
 
スタバ: Another one of the abbreviations that the Japanese are fond of, Starbucks.
 
ナチスト: Nazi.
 
チューター: Tutor.
 
バン: This is one of the weirder ones, since removing the last "g" makes it so removed from the original word, "bang".
 
ギャラ: Guarantee/fee paid to performing artists; I had big problems with this word, because when I first came across it, it was used in a context where the English meaning of "guarantee" wasn't appropriate. Only after a bit of digging did I get the second meaning, which proved much more suitable.
 
イメージダウン: Ruining one's image.
 
タラップ: Ramp. I have no idea where that comes from...
 
リュック: Backpack. Equally stumped...
 
サンダー: Thunder. This I was incredibly perplexed by; "sander", perhaps..? But in retrospect, it's obvious that the English "th" would be substituted with a simple "s" sound.
 
スリーサイズ: Three sizes, refering to bust, hip and waist. Well, where in the world could I have come across this expression? *whistles innocently* Oh my, looks like rain, doesn't it?
 
サビ: Refrain, chorus. This was another really tricky one. I had come across it on multiple forums, most in musical context, so I had a hunch it could mean that. In the end I eventually fould confirmation on the Japanese Wikipedia, doing a search for the word.
 
ユーモア: Humour. Ha ha!
 
Bonus 1: Strange how movie titles can change across continents... Karate kid becomes ベスト・キッド, "Best Kid".
 
Bonus 2: Not strictly a katakana word, but something I came across, started wondering about and eventually found a meaning for: the phrase "kwsk". Seemingly random letters, no? Well, it's short for "KuWaShiKu", 詳しく.