These ten words are taken from a list of the most common Hindi words (courtesy of Hindi Google Group and Resource Center for Indian Language Technology Solutions). Two of them -- 51. गये and 58 उन्होंने -- are still mysterious, i.e., I didn't find a definition for them. I'll have to ask Pradeep and see what he thinks...
Common words in Hindi, numbers 51 through 60:
52. कभी ka-bhī (adverb) sometimes; at any time
53. आदि a-di (noun) et cetera
54. लोग log (masculine/feminine/plural noun) people, folk
55. बार bār (masculine noun) 1. times, occasion. 2. gate, door; doorway.
56. यहाँ ya-hāṃ (adverb) 1. here. 2. at
57. दोनों do-noṃ (adverb) the two; both
58. उन्होंने un-hoṃ-ne (pronoun) oblique case of they
59. कार्य kār-ya (masculine noun) 1. action, act; activity. 2. work, task duty.
60. पास pās (adverb) nearby
All translations made with The Oxford Hindi-English Dictionary.
Edit (15 August 2008): Updated with advice from Vinay and Pradeep -- see changes made in Errata, Words 1 to 100.